SSDI, the main disability insurance benefit from social security, is not means tested. People pulling in millions can get it too, as long as they’re disabled (and qualify from working long enough in social security paying jobs). Usually that means they’re too disabled to work, but might have income from their investments or other sources. SSDI isn’t means tested, but does look to your earned income to determine whether you qualify (after all, the disability payments are designed to offset the loss of earned income, but someone who does still earn doesn’t need that stream of income as much).

SSI is the other disability insurance benefit from social security, and is explicitly an anti-poverty program that is means tested. So you have to demonstrate a lack of income in order to qualify.

Note that you can collect both, with concurrent benefits, but the SSI means test looks to your SSDI income, that counts against you.

There are a lot of anti poverty programs with pretty abrupt cutoffs based on income, or earned income, or even wealth, but many of the disability based ones have less stringent means testing or no means testing at all.