You're saying "we shouldn't do it because the government would ruin it." I'm saying "the government shouldn't ruin it." To which you responded, "yeah but what if they do tho?"
I know all of that, and I'm not saying that this is the easy way out. But UBI is a much more effective and stress-tested way to introduce an effective social safety net to a capitalist society when done right. So I think we should do it right.