The first thing that comes to mind reading this is that 'corporate ladder' is the wrong visual concept. Corporate hierarchies are trees with root at the top.

The first thing that comes to mind reading this is that 'corporate ladder' is the wrong visual concept. Corporate hierarchies are trees with root at the top. The problem is then comparable to the academic world, where each PI will have a series of PhD students who themselves want to become PIs, but the PI replacement rate is too low to accomodate this. Unless the global academic world is expanding, inevitably the majority of PhDs will not become PIs. One general solution is to flatten the hierarchy, which ultimately would reduce the spread in compensation and rewards from the bottom layer to the top layer. This would make promotion somewhat less attractive particularly if it came with heavier administrative responsibilities (generally less fun and more hassle).