The Ethereum community started talking about this five years ago, which spawned a multi-year effort to move to "Proof of Stake" and stop using large amounts of electricity forever.

The first phase of this effort launches later this year. It's currently undergoing a public testnet. https://medalla.launchpad.ethereum.org/

Since 99% of blockchain app activity occurs within the Ethereum ecosystem, and Ethereum is dropping proof of work, we should put to bed the idea that crypto industry insiders don't care about this issue or aren't doing anything to solve it.

Exactly. And PoW systems have built-in dampening ("difficulty") that make sure you need to burn even more energy as the system gets used, just to stay where you are.

I sometimes joke that Bitcoin is the closest we've came towards defining trust as a physical quantity - with the unit being watts. You can get a good approximation of the lower bound of the energy costs of trust by just comparing it with a trustful system that is regular economy. In other words, that is how much energy is saved by not pursuing trustless systems. Trust is a very powerful optimization trick.

They do, they blabber about how it's not actually waste because people value the waste. It's effectively a logical extension of the marginal value theory applied to ignorant self-destruction.

While they will talk about marginal value, they don't talk about entire systems incentivized to operate by creating value destructively, aka externalization at its finest.

Not only that, the Proof-of-work system also is prejudicial to holders. Miners are constantly dumping their newly mined coins to pay for there astronomical electricity bills. (constant selling pressure isn't good for the price)

Also, most of the mining power is always in china, so that isn't good. Mining is very centralized, miners can just join forces and 51% attack the network, which seems unlikely but not out of this world. It surely can happen, specialy if they find a way to be very profitable. 51% attack a network, or using exploits isn't illegal.