This. Bitcoin only remains secure if the amount of electricity being wasted scales with the price. (Otherwise, the payout for double spending would exceed the cost.) For it to actually be a viable store of value at global levels, it would require burning orders of magnitude more electricity than is currently even produced in a year. It mainly appeals to the kind of people who self-identify as being good at math, but who are actually too dumb to do basic arithmetic.
Costly doesn't mean that it has to waste actual resources. The chance of winning a block could be made to be proportional to the amount of bitcoin deposited into some smart contract, instead of proportional to the amount of electricity wasted. The outcome would be exactly the same, and nothing would be wasted.
From my short life as a tech guy, I have already realized that there is no 100% secure system. Companies try to hide information and avoid leakages; complicated systems of governance try to avoid malpractices while minimizing bad actors. In the end, it is always a dance between attackers and defenders. Bitcoin has the dumbest way of protecting itself from attackers. But by being the dumbest way, it is also the most predictable. It is like instead of coming up with sophisticated methods of protection that no one knows its weaknesses on the long run, Bitcoin only focuses on building a bigger wall. And that's why I feel more confident.
very good point - the entire reason for PoW is to "waste" something to prove you're invested in the ecosystem. If you can do useful things with that work, you're not really proving you're invested in BTC, but you may just be invested in whatever that useful side-effect is