I do believe that a tiny uncomfortable UBI would increase the overall economy, and benefit individual businesses by pre-weeding out a lot of posers.

If someone can get by on $500/month, and not feel the need to make the effort to live better, it would be a service to all to give that to them.

And on the other hand, a small fallback that makes it easier for individuals going through a rough spot to come back also helps the overall economy and individual businesses.

Finally, if we had a basic program like this started, the number could go up with overall economic productivity. Slow at first, but as the AI/machine economy takes off, especially with practical accessibility to off planet resources, a tiny fraction of the economic output would make everyone rich by today's standards, just at the time when human labor's economic value heads to zero.

The US already spends $1000/month per citizen on entitlements. If you just give everyone $500/month instead, you'd eliminate the deficit and have a few hundred billion leftover to spend on colonizing planets.