They don't want to risk their lives.
I'm not talking about violent revolution.
I'm talking about hundreds of thousands, then millions, of people putting Congresspeople on notice: here's what we demand, and if you don't do it, you're out of a job.
And not just calling or emailing or writing ONCE. Doing it weekly. "Just reminding you, Senator, we're against [whatever] or for [whatever] and we're watching how you vote on this bill and if you're serving your constituents' wishes or not."
No Congressperson can ignore hundreds of thousands of DAILY phone calls and emails, or ignore people who can and WILL vote for them (if they do what's required) or against them (if they don't.)
You just have to make them believe you're serious.