One question - why didn't Bitcoin drop to zero? I know, VHS survive and Betamax didn't, but unlike Betamax, Ethereum is pretty popular for everything, not just for low-class commodity speculation.
What distinguishes Bitcoin from most cryptocurrencies is that a) It has a (relatively) simple goal -- sound money -- and thus less attack surface; and b) Its community is fiercely conservative, to the point that major changes to Bitcoin (e.g. increasing the total supply) are completely off the table. These properties inspire confidence, making Bitcoin a much safer bet than any other cryptocurrency.
The narrative that is often pushed forward is that they have different use cases. Bitcoin is a limited-supply store of value (analogous to precious metals). BTC blockchain isn't well suited for quick transactions, but it is the blockchain that is the most robust and secure. Ethereum, being Turing complete, provides an ecosystem on which other applications can be built.
Both are valuable because of their universally recognized scarcity and value. If you want to put your wealth in a SoV cryptocurrency, Bitcoin is the clear schelling point.
Ether will remain competitive with BTC, it may even flip it in market cap, but I doubt Bitcoin will ever go away.
I don't think taxes justify the value of a state currency, otherwise the value would fluctuate wildly when close to tax season.
Ethereum's mining fees exceed Bitcoin's:
That would mean it has better long-term security prospects than Bitcoin, as security is proportional the revenue earned by validators.
That's why I said that Ethereum's long-term security prospects are better. Its mining fees have exceeded Bitcoin's and with the multi-pronged efforts to further scale Ethereum - that are vastly more promising than Bitcoin's - there is a high likelihood of these fees further increasing their gap with Bitcoin's.
As long as speculation is the main thing going on in crypto, BTC is king, since it is purely speculative, has the best name recognition, and doesn't try to hide that fact.
It's different from a conventional bank account, because there the returns are (theoretically) coming from the bank loaning it to entrepreneurs to buy factory and farming equipment and create value.
You could however be morally against earning interest through others speculating. In that case you could still earn better interest by just by being USDC-sUSD LP on curve.fi.