Being under the protection of a good L6+ is essential to actually getting anything done, launching, and getting promoted at a big company. Without it, you'll find that you won't get any cooperation from other teams, your projects will get canceled, and nothing you do will ever launch.
Staff+ engineers burn out at significantly higher rates than lower levels. I know a lot of Senior engineers that are quite content to just sit there and never get promoted, because the quality of life at that level is IMHO significantly better than at higher levels. Was talking with another recently-promoted Staff engineer (I'm Staff myself), and we were lamenting that Big Tech doesn't really do demotions, because the job expectations at higher levels get progressively higher, you have progressively lower control over outcomes, and the consequences for screwing up are significantly worse.