What can reasonably be done to help with the overpopulation of cats? Generally or with better funding of xyz?

Don’t want this to be anti cat at all! I have 3 rescue kitties and am just saddened at what things look like. Lots of posts from rescues or people trying to rehome and there’s no room for the cats anywhere… on top of the stray population. Of course TNR but that’s no small task and it costs money to people who are just trying to help and can’t afford to do more.

I guess just wondering? Not sure where more money would come from to help. Curious if anyone has any thoughts or experiences with things that could help.