In my experience non drivers underestimate the impact of their non driving on others.
I'd flip this the other way round: drivers IME underestimate the impact their car use has on others. Environmentally, cars are an absolutely terrible idea. If you want to do "your bit" then give up your car. Walk. Yes, maybe make your world a bit smaller and your life a bit slower - sacrifice a bit. Also, public transport is based on demand. So use it and keep it available for everyone, especially those who are less fortunate than you in terms of money or health.
I have friends I can only meet up in certain places because it’s dictated by where they can get to on public transport.
And this is a problem how? If they are local to you maybe you too could go on public transport. And maybe it would take twice as long. Invest in your local community - then you will have people locally who you want to see.
I think individual "it's mine" car ownership really highlights our individualistic society. It implies my time is more valuable and my children must do all these activities in different locations and if my,world shrinks that will make me a loser/my life less exciting/I can't do what I want all the time.
My job mandated I was a driver - when I asked at interview why I couldn't go to the different places on public transport, taking the time hit in my own time, they had no answer. And offered it to me anyway. And then I had a massive accident and now I can't cycle, walk slowly and painfully, and the public transport for work is a struggle. But I'm still doing it. I can't afford to run a car, but certainly it would make my life easier. I don't see that my convenience trumps the right of children to live in a world that is less polluted and congested though.