The number of interns->hires I've seen that, once they got an offer, didn't even bother interviewing elsewhere is astounding. Then they stick around for 5 or 10

The number of interns->hires I've seen that, once they got an offer, didn't even bother interviewing elsewhere is astounding. Then they stick around for 5 or 10 years. I've told many of them that they are doing themselves a disservice. I see many carry intern shenanigan baggage with them for years, limiting opportunity because they aren't taken seriously.