It's true that a small minority of people actually have a use (legitimate or not) for bitcoin, but as far as the general public is concerned this is not the case.

And appropriately it represents a small minority of energy use (~0.6%)

0.6% is orders of magnitude larger than the percentage of people who have a legitimate use case. In my opinion it's not that coin does not have legitimate uses, it's that the cost of providing those uses far outweighs the benefit by design.

The current increase in value and ramping up of energy use is not due to an increase in the usefulness of the coin, but instead on a renewed interest in the game of hot potato that is speculation.

Exactly, hoarding bitcoin —not using it— is the problem. It leads to high prices and consequent high environmental impact.

You mean saving, which is actually a use contrary to what years of keynesian propaganda have made you think

Couldn't this be met with a proof of stake coin? I could at least tolerate a PoS cryptocurrency because it at minimum consumes orders of magnitude less energy than Bitcoin would.

Hopefully. I think proof-of-stake is a promising technology but I'm not certain yet whether it can fully replace the security guarantees provided by proof-of-work. But if it can, then of course that would be excellent. Not only would it reduce the consumption of cryptocurrencies but it might even offset some of the energy usage of traditional financial instruments.

Some possible issues with proof-of-stake though are: Does the ability to borrow money to stake (since you get it back after exiting) make it too easy to conduct an attack? And, since you can't stake if you have no coins, will it be too easy for entrenched stakers to control the supply later on?

It could. But so far, no PoS coin has ever survived a bear market. Look at Peercoin and Novacoin as examples.

And that right there is probably why Bitcoin is going to persist. They can't afford to become poor themselves easily. So it was never about the technology and all about keeping an entrenched position at all costs.

Things could be different this time around. Polkadot and Cardano are leading the way in PoS and Ethereum might conservatively copy the parts that work. But they could turn out to be just like NavCoin and PIVX after a few years — much lower on the marketcap chart. I don’t know what the winner will be in the future but I do know quite a lot of the past.