It's true that individual actions to help the climate may not help a lot, immediately and in practical terms, if there's no bigger policy movement.
Then again, seeing that people are willing to take costly individual actions is a strong signal to elected representatives that their electors care about this stuff. So it still may not be worthless.
China’s Greenhouse Gas Emissions Exceeded the Developed World: https://rhg.com/research/chinas-emissions-surpass-developed-...
Let's take some other anti-social behaviour as an analogy. Imagine person A is in their car, idling their engine, outside an elementary school at pick-up time[1]. Now imagine person B comes up and asks them to stop. How well do you think that works if person B gets out of a car which is also idling its engine when they come and make the request?
Your argument seems to be that person B's car is smaller. I don't think that helps much, but it's also not in any meaningful way true. China's emissions are large only because China is large. Per-capita emissions are what matter here (otherwise it would solve the problem of China being a large emitter if China were to split itself into a dozen smaller countries — which is clearly nonsensical). China's per-capita emissions are less than half those of the US[2], and some of them are emitted in producing goods for export to the US.
[1] I live opposite an elementary school, and this is sadly not unusual.
The niche between current temperature and end of the world temperature will be exploited by growing nations until something is done about rich countries exploiting their low cost production to work around green laws
I'm done recycling, reusing and downsizing until legislation is enacted to prevent my effort toward the environment to become someone else profit.