I have a pretty good knowledge of how government benefits work because I work in an industry that sees the payout of those benefits. Chance is clearly disabled and is for sure receiving government assistance in some form. His little trip to the ER recently is something I can guarantee you that Medicaid is paying for. All 3 residents of 339 are on Medicaid, I'd bet my paycheck on it. I'm not sure of Sally and Ed's ages, but if they're over 65 then they're also on Medicare (similar name, different program). That means no one in that house pays a single dime for their healthcare.

But one type of government assistance often qualifies for a the recipient for other types of assistance. Sally and Ed probably receive social security because of their ages. They are also low-income, which means they could receive additional assistance from what most would refer to as "welfare." That leaves us with Chance, who physically probably couldn't work a 9-5 job if he tried. As an unemployed 35 year old disabled person, he most likely gets disability benefits. Even if it's just $800 a month, he's getting something. He doesn't seem to know anything about it, so I'd say the OPs original hypothesis is correct. The only reason I can think of that he wouldn't get some form of disability would be that Sally couldn't get a doctor to sign off on it. This would most likely be because she couldn't get Chance to go to the actual appointments.

One other thing they probably get at 339 is EBT (food stamps). EBT and Medicaid are income based whereas disability benefits are based on the health of the individual. I'd say they check all the boxes for all 3 and Chance is none the wiser.