I don't agree, at all. I went to the same school as many poor, middle class and rich people they had the same education as I received, so why don't they have the same ability to gain wealth. Basically they can.
There is zero stopping anyone who attends school from trying hard, going through university and becoming a doctor or whatever else they want.
Alan Sugar types are rare, simple because stupid people rarely get of their arse and realise they need to try harder. You cannot make excuses for the vast majority of poor people based on disability or drug abuse. Millions of people are not druggies or disabled they simple just are thick. Hell I don't even blame them for that, that not there fault. It could be genetics, it could be because their parents didn't help them at school or the system failed them, all the things you say are probably the catalyst for the being that way, but it still boils down to poor people are poor for a reason. I would hassen to say that geniuses don't stay poor for long if they ever become poor.