There's an AI in My Right Brain

At first, Pigfoot was in his forties and had accomplished nothing, so he started running takeaways because he was drugged and looked stupid. Moreover, bad guys don't become gangsters all at once. Later, they are reborn in the body of a top student. Decades of experience, coupled with the transformation of the system and the top student's brain, have created a pig's foot with an incredible IQ.

I can't understand the connection between the first few chapters and the following chapters! The protagonist is described as a fool, and the villain is described as a gangster. Later, the protagonist is described as a bit mature and steady. . .