With PoS, the more coins you hold, the more power you have over the network. Now think of the huge exchanges such as Coinbase and Binance — think about how much power they'd have. Bitcoin with PoS is simply a disaster.
Can't argue with the many similar posts that POS is not an option for BTC. While other coins have this proof-of-stake mechanism BTC is simply too valuable to engage in such without being detrimental to the rest of the holders.
Remember, BTC is all about decentralisation and moving away from the 'one man' monopoly.