In my case, I get the impression that it’s both.
Once during 2020 I got a phone call out of the blue from the technical manager. “Hey, would you like to be our new <first name of the one who used to hold that position>?”. Turns out my predecessor was looking for greener pastures.
When I told some coworkers about this, their reaction was “And you said yes??”
It’s been four years now. Changed to a new employer last month, but I’m doing the exact same stuff, and I enjoy it.