But, a stake has to be at least 32 ETH, where at $1650/ETH lands you at $52,800. So, the validators have to have a significant investment in the platform, more than your average investor, and far more than anyone simply owning ETH. While I don't necessarily agree with the centralization arguments, I do agree that it is a far smaller group of people than you'd think.

Even that isn't accurate because many groups and exchanges will aggregate eth from users. Then users with far less than 32 eth are participants in a stake through their chosen representative.

Again, no, not the people putting up the stake.

I am asking about the people with the power to declare that people who put up the stake were dishonest in their validations.

There is no such a power, slashing is 100% decentralized.

The key innovation in modern POS systems was figuring out how to do this, it is a solved problem.

The code - not the people. Trust but verify - just like all other FOSS.

The people who are running the slasher nodes

If I understand what you mean by "slasher nodes" (there is no such term in reality): Anybody can run a node that checks for conflicting validation messages and get a small reward by doing so. There is zero stake required to do this. It is not some power conferred to "vitalik and his friends"

$52,800 is a pittance compared to any remotely significant mining operation

you don't need mining equipment to validate transactions on bitcoin, nor do you need to own it. With ETH, you need to own 32 ETH, obviously.

Absolutely not the case. You can verify the transactions without owning any ETH, you cannot participate in the reward process for your efforts though for that you need to be a validators and put up your stake.

The parallel with Bitcoin is quite strong. You can run a Bitcoin node without running a miner and verify the chain but you don't get rewarded. You can run an Ethereum node without staking and verify the chain but you don't get rewarded.

There is a confusion in language used. Bitcoin has two types of actors: block consumers and block producers. Ethereum has three types of actors: block consumers, validators and block producers. Thing often described as "full node" does just that - it consumes blocks, checking if blocks are valid. Ethereum validators are different, they not only consume blocks, they also attest their correctness for the rest of the network.

Who validates the validators? The other validators?

No. Their role is a bit different. They exist to prevent so called nothing-at-stake attack. If each block has to be signed by known parties (parties selected in a way attackers can't control), and those parties are bound by slashing rules (signing two different blocks for the same height is grounds for slashing), than it is very hard to pull off nothing-at-stake attack and create an alternative chain.

Not the people putting up the stake. The people with the power to declare them liars who lose their stake.