It's not that he actually particularly wants to marry a rich guy, any more than he wants any of the other options he could take. 

It's just that, well....what other options? Going home with someone new every night because he doesn't have anywhere else to sleep, hoping that someone will like him enough to let him stay long-term and he can make it last without getting seriously hurt? Hoping from job to job hoping to find something that'll take someone with barely any work experience and will pay enough for an apartment? DV shelters aren't an option, he knows where in this city they are; regular shelters are the obvious place for Sasha to run, so he stays away from them. 

So when he gets a call, of course the answer's yes. What else was it going to be?