I went to see him again in the late noughties and he was haggard (not surprising, given he was around approaching 60 and always working heavily). He said he'd lost his spark to teach, and that current day students just weren't interested in doing the work - it's hard to be passionate when you're teaching uninterested people.
He said that my group's era was a great one for teaching. I accused him of blowing smoke up my arse and how bad could it be? These things are hard to make metrics of, but he gave the example - out of a course of 60 people in my final year, there were two applications for 'special consideration', one of whom was an eight-month-pregnant woman who didn't want to risk disturbing exams in case she went into labour. 'special consideration' was used for serious issues - close relative died, that kind of thing. By comparison, the current year had around half the students asking for special consideration.
He had other stories of change as well. I started a PhD under him (quit it early when I realised I would be relegated to academia) and we were treated as cattle by the department, mere cash-cows to bring in money. He mentioned that when he did his PhD in the 70s, doctoral students were considered gold and pretty much equivalent to a member of faculty. Now (late 90s) they're packed into an uncomfortable broom closet and their resources are, quite literally, commandeered by admin. As a literal example, we saw one doctoral student have her work stalled because the number crunching machine she had incoming was redirected to an admin temp.
These days it doesn't quite work like that; lots of kids are there to punch their ticket. Ticket-punchers aren't motivated to do any more than the minimum. So yes, perhaps I've overlooked the other half of the equation.
A friend of mine is a teacher and I moonlight as an Olympic-style weightlifting coach. I once enthused to him that I could see the allure of teaching. He sighed heavily, then pointed out that my trainees want to learn. Of course I enjoyed it.
Many of my coworkers (in higher ed) would rather be teaching. But it just doesn't pay.
YMMV
Some professors love to teach and everyone remembers them fondly. I had one professor who'd taught about 2/3rds of the courses at my university over the years. You could always tell he'd taught a course in the past because subsequent professors always retained the assignments he'd created -- they were just too good to replace.
I was lucky to have him as my honours supervisor.