I think POS wasn't the reason ETH become popular instead it's an attempt to mitigate it from scaling issues and also for eth in going greener, meanwhile even when eth was still POW it was so popular that even the fee increase so high. the POS was part of the solution in effort to decrease the scaling issue in which has motivated many coins to become 2nd layer solution.
and so far it seems this works, not solving the problems entirely, there's something still need solution.
POS It's not the main reason for ETH's popularity, POS is only a trigger for ETH to be in demand again because the migration made from POW to POS makes fees cheaper and transactions are confirmed faster. ETH always had fee issues at first when the spike in transactions was happening, but now that's not the case anymore. Become a solution and create layers for ETH and several other networks that follow in ETH's footsteps. But there are still many problems that ETH has to solve, it is still in the development process. and so far it seems this works, not solving the problems entirely, there's something still need solution.
