At some point when stymied in my career I thought of getting an MBA. I plunked down (while pulling shifts in an exhausting job) with a 20 dollar GMAT prep book and studied for three months. Got 760 out of 800, first try. No fancy tutoring. This after in high school I never got high grades, because I learn best independently. This in a sense is the American model, which believes in redemption at any stage. The SAT, GMAT, etc are a great meritocratic leveler. The European model rarely includes such tests, preferring a much more conformist system which prioritizes early tracking.

I didn't go for the MBA in the end, mainly because it was not really my dream.

The main drawback of the US system is that the main limiter is financial, rather than social.