You're arguing that the actions of individuals have no impact on the collective actions of humanity, the sum of 8 billion individuals.
Similarly, you probably never had a conversation where someone said "Gee, I'll stop burning fossil fuels now!" But when you use public transportation, or patronize businesses on foot, policy makers are motivated to continue supporting such options. Not for you personally, but for you and others like you.
I prefer to donate time. I'm now president of one local non-profit (in addition to my paying job), and a regular participant in another. Sometimes I'll donate supplies that we need, but never money.
If a time comes when I have little time and a lot of money, maybe I'll switch. Donors are necessary. But I know that we need hands more than dollars.
Why do you think BP produces emissions? They may be evil, but it's not out of malice, it's for profit. People, like the 26 million residents of Australia, pay BP to give them more fossil fuels.
A top-down response, where governments just outlaw all extraction and burning of fossil fuels, would be a lovely, quick solution to the climate crisis. By all means, try and make that happen, but I wouldn't hold my breath.
One thing you can do today to make an impact is to adjust your lifestyle to give less money to the fossil fuel industry. An individual carbon footprint is small compared with a company, just like the money they give to BP is relatively small, when compared with their total profits. But when you add up all the customers, their money adds up to the revenue of the industry, and their carbon footprints add up to the footprints of the relevant companies.
Oil companies sell oil and manipulate national policy to promote its use. Consumers buy it and support policy to promote its use. There's at least a bit of room for personal responsibility there.
I'll add dancing to this list. It's certainly possible to just show up, do the steps, and leave, but it's an atmosphere where talking to people is very easy.
If you go to a class for a few weeks/months, you'll start hearing about other classes, or events. You also might end up finding that you have other connections with some people who you dance with.
I speak from experience here. I'm not very good at people, started dancing for that reason, and my time dancing has helped noticably, according to an old, long distance friend.