If everyone did it, it'd make a noticeable impact. That impact isn't enough to fix things, but thinking "oh well I won't do anything because they're not doing a

If everyone did it, it'd make a noticeable impact. That impact isn't enough to fix things, but thinking "oh well I won't do anything because they're not doing anything" is not the kind of thinking that will get us to a solution. Act to your capacity and trust that everyone else will do the same. Either you will be right and things improve quite a bit, or you will be wrong and things improve very little. In both cases at least you've stopped making it worse.