Hedge funds who short shares do actually provide a service to the investment community in two ways -
- they provide liquidity in providing shares to buy
- they do some price discovery work and present an alternative view to the idea that share prices only go one way (not always well done, but that's a another argument)
When they get it wrong - as apparently Melvin Capital did then they make huge losses - but then no one said that Hedge fund managers know everything, well except Hedge fund managers
And if enough small investors are prepared to buy shares at $200, $300 and lose their investment well the Hedge Funds will learn a lesson and maybe provide better price discovery for a while