Small changes can be important if enough people do them, but even if they donāt a small change is still a small change, with other benefits beside global ones.
A simple example might be to eat a little less, you will lose weight, be healthier, feel better, it might take a little while, but is mostly true for most people, it could rub off on others that know you etc.
But yeah, it can be difficult to stick to things, avoid external influence and so on, but if you donāt try then you donāt know.
I often think we can look to others to be the saviour, or set the example, or take the blame, we tend to look at things this way, but truth be told everyone has it in themselves to do a bit better if they want to, but it involves a bit of sacrifice and compromise, and a realistic attitude as well.