I remember a quote along the lines of "you won't change the system from within, but it will change you."

reminds me of the first election after the counterrevolution in hungary, so 1990. a lot of starry-eyed idealists (with real morals) got elected and got filtered out or demoralized over the first 4 year cycle. by the second, it was purely just the slimy fucks getting elected.

Kind of like how good cops inevitably either stop being good or stop being cops.

I think most people with that arc were cynical and self-serving in their "community organizing" phase. Careerists, basically, gathering credentials and connections. There are a lot of people like that in "leftist" groups and unions and they are probably the most dangerous people in those groups, as anything disrupting their work (like a reasonable deliberation on what projects to focus on) threatens their personal trajectory. So they will fight, often in unprincipled ways, to keep that planned trajectory.