How do you think proof of work operates now? Do you think big mining operations don’t take massive capital? They do, and also waste ungodly amounts of power at the same time.
POS only works with an active economy i.e. validation requires something to validate e.g. consumers using ETH to buy goods and services. This implies the general population has access to large amounts of liquidity of the currency.
A new institutional investor just needs to start hoarding that easily accessible liquidity and the biggest players in the space will need to give up their share or risk the price of the currency dropping to zero because it’s too hard to transact in it and therefore it’s no longer profitable to tie up 32 ETH and run validators.
You're conflating bitcoin mining with ethereum mining. Anyone with a GPU can mine eth and therefore the capital requirements are far lower. Now, of course if you want to make big money, then that requires big capital... but that could be said of nearly any business out there.
