I would have quit at the Christmas party, after everyone ignored your asking for help and treated you like a paid servant, or a menial/suck-up/groveller/defective slave, who is too dumb to demand payment for their services. You would have been perfectly within your right to walk out in protest.
Unfortunately most of the organisations I have volunteered with (mainly gardening, pet and women's charities) have been desperate for volunteers to step up and run things, and put pressure on new members to "do their bit" before they even know what is required. Those that are generous enough to agree to take on a role are rarely appreciated. Much more likely to hear complaints and unfair criticism than any kind of gratitude or appreciation.
The kind of people who persevere under those conditions often have their own psychological reasons for doing so, which often makes them very unsuitable. You meet some very strange types. There are usually one or two lovely people, who make it worthwhile, especially if it is something you are keen on doing yourself, and with the right balance of people it can be very rewarding, but sadly your own experience is more then norm than the exception.
With absolutely no previous experience I got roped into running the finances of an allotment society, quickly having to learn double entry bookkeeping and all the laws and regulations, pay our bills, and chase people for their annual rents. A thankless task, and the second year, when I returned from my holiday I found that rumours were being passed around with great relish accusing me of having taken people's allotment rent and not entering it into the books. Which I found out when I was hauled in front of the board to account for my actions.
This turned out to be because of one old Kurdish geezer (who had previously tried to bribe me with produce from his allotment, seeming to think I'd be so appreciative that I'd "forget" to ask for his annual rent) had told one of the committee inquiring into why he still hadn't paid that for year by August when we were all supposed to have paid by the end of March. He insisted vehemently that he had paid me the money in cash, months ago, and he didn't know what I'd done with it if it wasn't on the books!
When I got to the bottom of it I confronted him very publicly and quite angrily, whereupon he shrugged, smiled in what he probably thought was a charmingly roguish manner, and said "I paid last year" as if that was a reasonable explanation.
I announced then and there that they would need a new finance officer for the next year, because I would not be taking on any further voluntary roles on their behalf, because I was so upset by the way so many of my "friends" had been so quick to believe and spread the delicious rumour that I'd been trousering the rent payments instead of adding them to the books. Perhaps I should have suggested that they elect the lying old git who was so willing to blacken my good name in order to get out of paying the (very low) annual rent?
Some societies make it a condition of membership that you take it in turns to do the work of running the society, but most people who join don't have the time or the energy, and others just weaponise their incompetence until someone else is forced to take over. I doubt that situation will improve with so many women now in full time employment, and the retirement age being pushed to a point where many people are burnt out and exhausted by the time they finally get to retire.
Against my better judgement I volunteered for a women's organisation, because according to their constitution they needed 6 women's names on the governing committee. The wheedling claim (by the paid manager of the organisation) was that this would be a paper formality, they just needed "6 warm bodies" on the governing council, to be able to tick the right box to keep getting funding. Hah! This time I was a lot more cautious, but within 5 years I somehow found myself dragooned into the position of chairwoman (a position I am completely unsuited for) and again being taken advantage of, unappreciated, and gossiped about.
I did learn one very useful trick during that time though. Whenever someone cornered me to tell me how the organisation could be improved (usually with plenty of suggestions that would have required a lot of work from whoever got stuck with the task), I learn to respond with "how soon can you start implementing those changes/making the arrangements?" Funnily enough not one of the people making the brilliant suggestions had the time or energy to actually do the required work, they reckoned they'd done their bit by telling the chairwoman and from then on it was her responsibility to bring the idea to fruition, and face criticism if she failed to carry it off according to their expectations and demands.
It's a shame, because taking part in organisations that improve people's lives (including your own) can be very rewarding. I'm a tough old boot with very firm boundaries, but I managed to reach 40 without ever suspecting (even in my wildest dreams) that someone would try and get out of paying their tiny annual allotment rent by claiming that the finance officer had collected the money and trousered the cash. Only to shrug and say "I paid last year" when confronted with the lie. Sadly far too many people eagerly snatch any advantage they can grab, while many more will make endless demands but refuse acknowledge the time and work that would be required, but with a very keen eye for anything that doesn't get done, or isn't handled to their satisfaction.
As thankless tasks go volunteering is not the absolute worst, because you always have the option of telling them to stuff it, and walking away with your head held high.