This actually seems very common in office jobs where you find many workers with million dollar salaries. Wall Street firms, strategy consultancies, and law firms all use models in which salaries expand massively with time, with high attrition along the way: the "up-or-out" model.

Even academia gives tenured positions (which have enormous value to workers) only after trial periods as postdocs and assistant professors.

Main Street corporate executives have to climb the ranks.

I think the financial industry is like this. Sure, the starting salaries are decent, but it's nothing compared to what you get if you make partner.

Sounds like a startup! :)