There is whatever pressure you bring to bear on it. As long as you are still living in a democracy your vote is the pressure you can apply. If the parties that exist won’t represent you, make new ones that will. Do something rather than deciding it’s both impossible and up to other people anyway.

I also don’t understand why UBI is desirable. Putting everyone on welfare means everyone is poor. This won’t end well, and it’s certainly not the case that 99% of the population will let a tiny number of people remove their income in favor of pennies for all. Political violence will come first, easily.