Allah has given us feelings, willpower, and thought processes. This is sufficient to justify what we choose to engage in something good or bad. I find it very confusing why in Islam there exists 'Shaitan'. For every bad act, why we blame Shaitan and not ourselves.
We do not blame Shaitan for bad acts:
And Satan will say when the matter has been concluded (Day of Judgement), "Indeed, Allah had promised you the promise of truth. And I promised you, but I betrayed you. But I had no authority over you except that I invited you, and you responded to me. So do not blame me; but blame yourselves. I cannot be called to your aid, nor can you be called to my aid. Indeed, I deny your association of me [with Allah ] before." Indeed, for the wrongdoers is a painful punishment. (14:22)
The Quran says that ultimately the fault rests on the sinner, and they will be punished for it. All Shaitan can do is invite people. Some people accept his invitation and commit sins:
He [Shaitan (Satan)] makes promises to them, and arouses in them false desires; and Shaitan's (Satan) promises are nothing but deceptions. (4:120)
And say: O my Lord! I seek refuge in Thee from the evil suggestions of the Shaitans; (23:97)
It is good to know at first what a "shaitan" is. Literally it comes from the root word that has a meaning "impurity". Shaitan refers to a rebellious entity, it can be a human, jinn, or something else. It is a common word, in contrast to some "specific entities"; e.g. like vehicles; it can be a car, bike, or drone.
In quran it is mentioned:
And thus did We make for every prophet an enemy, the Shaytans from among men and jinn...
[Surat Al-An'am (6):112]
Thus it is clear that a shaitan is like what I've mentioned, human or jinn (what is jinn by the way?). Following your question, you can now deduce why there is a concept of shaitan in islam. In fact, for every bad act the sin goes into the sinner, not even any jinn or something; there is no concept of "borrowing others sin" in Islam.
Furthermore, the term shaitan can also mean some entities that bring bad things to human such as some microbes (in some specific condition and place). There is some hadith related to this. See also: