They all say the course load and work is a joke. It's mostly an accreditation to the buy side hiring process and networking.
Either they're total outliers, or you're talking about something like an exec MBA, or something else altogether.
[1] https://www.usnews.com/education/best-graduate-schools/top-b...
It's by no means necessary, you'll find people at those firms without MBAs - a close friend of mine made the jump directly from banking and is well above the salary range I mentioned, but a top tier MBA helps.
It's also worth noting that a majority of compensation from these positions is from the carry on the person's fund (or a blend of all funds, like Blackstone does) and is based on fund performance. This isn't their base or otherwise guaranteed salary.
I will say that I think a lot of people can benefit greatly from learning basic accounting, finance, statistics, and microeconomics especially people who want to be entrepreneurs. But you sure as hell don't need to attend an MBA program to learn these things. Also, a lot of the other MBA coursework around things like marketing, global trade, operations, and management is either not even close to practical in a small business environment, assumes you'll be managing people who actually know what they're doing, or is useless without actually having significant real-world experience to match the theory.
The two most popular post-mba paths are investment banking and consulting, I know exactly what the post-mba IB comp is:
1st full year associate: 150k base, 70-100% bonus
VP comp is easily above 400k
Consultants make $165k+ base with slightly smaller bonuses out of school
The numbers schools put out are not contextualized. The high paying roles out of the top ~20 MBA programs command total comp that is almost totally unacheivable as an employee, even in tech, especially if you don't want to count on equity appreciation.
And regardless, still a far cry from what OP was claiming.