Power and equipment requires more work to get, maintain, and move out of the "position" should you want to exit. At scale, it's a heck of a lot of real world and varied work. Yet the barrier to entry into PoW mining is relatively low.

With PoS, I don't need to do much except possess (or acquire) the underlying token (and usually more of the token than any outside, non-cantilionaire would possess).

Perhaps most importantly, both systems require anchoring into reality with time. PoW can use the work to gauge time. PoS has no such feature to gauge time so at best it requires voting on time which is self-referential and isn't an anchor into reality at all. It's like anchoring a boat to itself - fine only if the seas are unrealistically calm.