I figure he'd be more like Stick in that he gives up having possessions etc that could hold him back. Stick seemed to imply that he should give up his apartment too in that episode. Also, being on the street for most of the day would give him a unique insight to what's going on. He definitely would have noticed the Russians sooner, and would probably know the repeat offenders and petty crooks as well as the dudes who work for the mob.

So yeah, in my head he's mostly homeless by choice. He can get money by doing odd jobs and stuff, because this is Matt and he's not helpless, but he made a conscious choice to not tie himself down. It also makes it way more difficult for people to find him and hurt him, since he probably has more than one place to go if he needs to lay low. He also knew about those access tunnels in that one episode, and he'd be well suited to find his way around those without light.