This is an exceptionally bold claim. Sounds dubious.

> Finally, many people have very successful careers in one field despite having a degree in a completely different field, which suggests that whatever people learn in their degrees doesn’t really matter all that much.

No it doesn’t. For that to be true you would need to demonstrate that, say, having an engineering degree does not influence likelihood or magnitude of success in engineering careers.

In reality there are likely going to be many recipes for success. Nepotism or social skills is one. Learned Competence is also one. Dumb luck is a third. The fact that you can succeed without such things does not mean such things are worthless

>...many people have very successful careers in one field despite having a degree in a completely different field...

This sounds a great deal like transfer learning. Applying format, structures, and approaches to unrelated fields. Much of an engineering degree is designed around learning to learn well. That's the only degree I can speak of, but it has been my understanding that other programs have similar intent.

You need to talk to lawyers and doctors too. Lawyers typically know jack shit about the law outside the fields they practice in. Doctor education varies greatly between countries. For example, in Poland medical school is whole 2 years longer than in the US, and the students have to learn all Latin names of all possible bones and muscles in the whole body. Every doctor will tell you that it’s absolutely useless in their actual practice. Do the two missing years make US doctors 25% worse? Clearly not, doctors forget most of what they learn anyway. It’s not like your rheumatologist remembers symptoms of all those rare internal diseases they had to memorize for the test.

Applying format, structures, and approaches to unrelated fields. Much of an engineering degree is designed around learning to learn well. That's the only degree I can speak of, but it has been my understanding that other programs have similar intent.

And engineering students, especially from top programs, typically are great at that, but not because they learned it at university, but rather because you need to be really smart to get into and successfully graduate with science or engineering degree.

Many people in western countries these days, especially the smartest and best educated, have extreme hard time accepting that innate differences in cognitive ability is a real, observable thing, and consequently their models of reality are deficient, because they put the causation on wrong factors.