From what I understand, the protocol can't efficiently handle that level of use. And even if it could, increasing use would likely drive the price down bc nobody wants to be the guy that bought a pizza for 2 BTC years ago (equivalent of $100k now).

The store of value/"eGold" use case is more relevant. It doesn't have the physical utility or intrinsic value of gold but the blockchain technology ensures that BTC can reliably change hands between people, at whatever price the BTC market feels it's worth. I think people will always find value in that and BTC will be the agreed upon form for crypto-wealth.

The other cryptocurrencies will likely have more direct day to day applications, but I'm not as confident as to how that influences the price of the cryptocurrency.

But still, I have some money in ETH because they're doing interesting things with it in terms of decentralized finance that make the speculation more interesting.