Onlyinyourdreams XR is actually mainly made up of people new to activism, in my experience of them.
I am a 'professional activist' in the environmental sector. I work in a very serious, highly demanding job (not in frontline protest - there is much more to environmental advocacy than protest.). I have two degrees, one of them in law, and work alongside some of the smartest, most well-educated people I have ever worked with, including high-profile journalists, scientists, analysts, economists and many others.
We do this not because we couldn't be working elsewhere, on far higher salaries. We do it because climate change is an issue of crucial importance for everyone, and it needs to be prioritised by governments and corporations if we're to have a future worth living in.
Check your prejudices.