Urgh this rings way too true. I've witnessed this happen too many times in the past few years, since getting involved in the BM community, a makerspace and starting our own plastic recycling non-profit. Even if you don't get demonized, you just start sinking hours into a volunteering black hole with no-one helping. So then you sink more hours into recruiting people to help, to find out they ghost the organisation immediately and you're back to doing everything.
It really sucks, because I hate how everything these days is so transactional. But if there is no exchange of money, people have no qualms about wasting your time or not appreciating your work. Value is seen in monetary terms, and your volunteering time is judged worthless by outsiders, while feeling entitled - maybe because they assume you get an immense amount of satisfaction from it?
It's been especially hard in Covid times, because now people are left with only the boring remote work side of things, without the social aspect (beer after a meeting/organizers cookout / whatever) that redeemed the thanklessness a little.