I love that analogy. No, you're not going to personally save the world by reducing your carbon footprint. But you know what you are going to be? One leaf on a tree in a forest, making that little bit more oxygen that helps collectively make the world a better place.
And that's worth doing. Especially if you can encourage other people to be leaves too.
That's completely fair. Individuals did do a lot to change governments minds for the ozone layer. However, there are a lot of people who think that buying into oil companies' propaganda and recycling or driving electric cars or whatever is the way to drive such systemic change, sadly. Instead of course (as the oil companies intended), all it does is make people feel good about themselves so they're not motivated to do anything to actually solve the problem.