The argument for defunding the police (that I agree with) is that crime goes down when you address the root cause: poverty. The money spent on policing could more effectively lower crime by being used for building healthier communities.
I think the largest part is either due to being caught up in a bad social set, or straight up because they think crime is fine. Poverty doesn't cause this, at least not primarily - it's rather that personal characteristics such as lack of impulse control and high time preference lead to both poverty and a propensity to crime.