How could it be in any other way though? I just can't get into the viewpoint of people who are surprised. Did they think that getting to tenure is just a normal, default stage in life that you will progress to as a natural consequence of time passing? Do they also think that everyone who works for long enough at a company will become a manager, then a VP then a CEO and if not, then they either did something wrong and worked below expectations or the system failed them?

Who starts a PhD and believes strongly that they will with high likelihood become profs? You have one prof as your supervisor and the same prof has many more PhD students. Do people not notice this?

After a certain point of bloat, growth cannot be sustained. Especially in America the system has ballooned up to an unreasonable degree and will collapse when people realize that value is elsewhere and will refuse to pay into the system through tuition.

Prestige, status, attention, fame etc. are scarce resources. Not every garage rock band can become superstars, most will not even be able to sustain it as a job or even to earn nonnegligible money.

Prestige is zero sum because it is relative. If everyone can become a professor then being a professor will inflate its meaning (already happening). But be assured there will be new concepts to signal prestige and people will be disappointed that they aren't all getting that prestige.

Yes, you're totally right. I think in general people do these things because they think they're special. You could ask the same question about why people found startups or attempt to become olympic athletes.