Term limits mean lobbyists end up running things. I’d be okay with age limits, but that would mean amendment, and it isn’t going to happen.

A safe seat doesn’t mean forever (altho California leans D and has been rejecting the GOP outright ever since Ahnold’s budget crisis). Seats turn over more often than people think, but they also don’t often turn over. 

https://www.pewresearch.org/short-reads/2022/06/09/some-members-of-congress-have-been-there-for-decades-but-seats-typically-change-hands-more-frequently/