What exactly is considered gambling in the case of professional sports/gaming or any sports/gaming involving luck/chance?

Question

Conclusion of bounty: No answer. I could've sworn there was answer, but it didn't have any references and then was later deleted. Well can't say I'm really surprised or anything. It's not like this doesn't happen like even in Christianity or Judaism SE, where each of those have already those fancy banners (I assume fancy banners implies a higher level than one without, even if the one without doesn't have a 'beta' beside the title on the upper left).

---

Basically as I understand 'gambling' is sinful/haram in some/most (at least the mainstream ones I guess) denominations of Islam. But what actually counts as 'gambling', in particular for the following cases?

1. professional sports/gaming vs amateur (but not for money) vs amateur (for money)

2. luck/chance/'randomness' vs skill

Please cite sources. If this requires denomination, then I pick whichever denomination has the most adherents. I understand this to be Sunni.

Notes:

1. I have also read online there are cases about chance vs skill thing involved. Like if there's an element of luck (not sure about the degree like 50% luck? 75% luck? 10% luck?), then it's considered 'gambling'.

2. I've read in some sources that professional sports playing or gaming is ok including poker or bridge (not sure about professional rock paper scissors), but audience members betting on it is not ok. (This to me reads like Nassim Nicholas Taleb's skin in the game thing, which is very antifragile/neat/cool.)

3. However I've read in different sources that professional poker playing is considered sinful/haram in Islam. Apparently, this is because poker has elements of chance. However, I guess it would be weird if professional chess is ok, but professional chess variants that have elements of luck are not ok in Islam, say chess960, choker or dice chess, all 3 of which are actually played professionally. (Ignore the following bullet points (3.1) and (3.2) if luck/chance/'randomness' vs skill is irrelevant.)

   • 3.1. Additionally, I might argue that physical sports, like, say, basketball, have not really more elements of luck/chance as compared to say, chess960, but more elements of 'randomness' (Nassim Nicholas Taleb says: 'While in theory randomness is an intrinsic property, in practice, randomness is incomplete information.')

   • 3.2. Hell I might even go so far as to argue that physical sports have more 'randomness' than card games like poker or bridge. I know I should be able to explain 'randomness' more precisely given my reputation on maths and stats se, but I can't think of something right now.

4. 'Professional' here refers not only to those who have actually already achieved pro status but those aspiring to achieve pro status. In the latter kind, we may distinguish between games that are geared towards achieving pro status vs games that aren't, if need be (i.e. if professional gaming/sports is not inherently sinful/haram. Ignore the following bullet point (4.1) otherwise).

   • 4.1. Eg Alice aspires to be a pro in a certain sport/game. One day, Alice enters a tournament and having to pay an entrance fee in the process. Another day, Alice and Bob play the same game against each other but in a non-tournament setting, and they play for money. In the latter case, maybe the morality of Alice's action will depend on how serious the game is towards her goals of becoming a professional and how risky the game is. (Again, this entire paragraph kinda assumes all or at least some professional gaming/sports is not inherently sinful/haram.)

   • 4.2. There's actually some way here I believe that 'gambling' is actually helpful for (but not only for) those aspiring to become professionals:

   • 4.2.1. If you play for money, then you have some assurance of the seriousness of your opponent. If you can get a certain level of seriousness from your opponent, then you're ensured to have enough good enough practice for tournaments.

   • 4.2.2. You can see that it's a common thing for chess streamers to play for money or for some other stakes (eg loser gives up social media in some way to the winner). I mean, it's not necessarily gonna be that serious or interesting otherwise.

   • 4.2.3. Perhaps such seriousness is not so hard to find for games/sports like chess/chess960, where you can find many serious players online, but what about other games/sports like say basketball? You don't quite have to be a pro or aspiring to be a pro for this next part: Actually, my sibling is a sports scholar (sort of). In order to have proper games of basketball, my sibling joins the university sports team instead of joining some clubs or playing with whomever/whoever shows up at the public basketball court in order to have a higher level of seriousness from opponents in order to really be able to enjoy the game.

   • 4.2.4. In case my sibling was unable to qualify for the sports team, I don't see what's wrong with 'gambling' in the sense of playing for money in order to enjoy in the game anymore than paying money to see a movie or indulge in some dessert.

   • 4.2.5. I wonder if Islam therefore would say here, 'Well too bad for those basketball players. See you at the movies or the ice cream shop, or get another hobby.'

5. I've read in some sources that playing roulette in a casino is sinful/haram because it is 100% chance (well, let's say 99.9%) and therefore if there were any kind of 'professional roulette' it is illogical or at least sinful/haram. And then similarly, professional rock paper scissors is sinful/haram. (I really cannot believe professional rock paper scissors is a thing though.)

Additionally, please consider to evaluate these scenarios to help answer:

1. 2 amateurs play a pure chance game for money
2. 2 amateurs play a pure chance game but not for money
3. 2 amateurs play an abstract strategy game such as chess for money
4. 2 amateurs play an abstract strategy game such as chess but not for money
5. 2 amateurs play a physical sport such as basketball, which technically does have elements of luck/chance/randomness for money
6. 2 amateurs play a physical sport such as basketball, which technically does have elements of luck/chance/'randomness' but not for money
7. 2 amateurs play a card game such as poker or bridge, which technically does have elements of skill, for money
8. 2 amateurs play a card game such as poker or bridge, which technically does have elements of skill, but not for money
9. 2 professional rock paper scissors players play an official game of rock paper scissors.
10. 2 professional chess players play an official game of chess.
11. 2 professional basketball players play an official game of basketball.

In scenarios 9-11, there is 'gambling'/betting involved in the sense that the winner walks away with money (which is then used to pay for food, rent, children's tuition, etc) and the loser walks away with nothing (or a lower prize).

Scenarios 12-14. Replace chess with chess960 in respectively, scenarios 3,4 and 10. There is an element of chance involved (the starting position).