Some dude though about some basic concept of decentralization and that's it.
This was not some mastermind who created the perfect money system.
There are massive amounts of issues with Bitcoin in particular.
Alone one reason why Ethereum was trying to be ASIC resistent was to make GPUs stronger and allowing for more / better decentralization.
Plenty of people who are no longer able to recover their wallets (I know two friends having lost 150k$\initial investment of 10k$).
Fraud issues like you see in El Salvador.
The huge changes in value (no Bitcoin is apparently not stable and independent from the economic market).
And it doesn't even solve the trust issue. As soon as you wanna spend Bitcoin you need other systems like smart contract (which also doesn't solve the problem) or trusting third party.
The only advantage of Bitcoin is that's unregulated and everyone is taking a bit of it who is fast enough, rich enough or smart enough from everyone else who is not.
Cost of pizza is an example of buying power of bitcoin which is not the same as its monetary policy. I can not argue that the buying power has been volatile thus far.
I do suspect it will trend toward stability on a decades timeline.
You have a lot to learn then because your analogy is weak. PoW vs PoS debate is one of decentralization, power, democratization and control.
As for bitcoin being dated: it’s ossification is intentional. It is, by design, a predictable and reliable monetary system.