Why I’m so “against” Ethereum

The information is in the block headers.

> In ETH instead it is common to just download the result and trust it’s valid

Nope. You still have to download all the block headers from block 0 and check if they are valid, including the PoW and other hashes.. The blocks are basically tamper proof as in Bitcoin (but can also be vulnerable to a 51% attack)

Then that's where it all diverges from Bitcoin: in Ethereum, there are three merkle trees: one for the state, one for transactions and one for the transaction results (receipts). The roots of these trees are in the blocks, once you have these, you can verify a particular value of, say, a state value, without the need to verify each and every other value, by walking through the tree and doing a merkle proof. There's plenty of info on the web explaining how it works if you look it up, eg. Search for "ethereum state trie"

As for syncing, recently it improved a lot. I did it a few times last month with Geth on an old machine just to test it out. Synced within 2 days, a big improvement over the previous versions of Geth. And yes, it got all the blocks from 0 to current. Blocks by themselves are very light.

no, nothing in PoS requires that. just a sad state of affairs with most centralized insecure PoS coins these days.

> With PoW, you only get the consensus rules.

no, you can opt to get hash of the most recent block if you want to compromise your security.

> Either way, you're relying on a trusted third party for bootstrapping.

no, you don't have to rely on trusted party for PoW bootstrapping. if you're scared somebody has communicated consensus rules to you incorrectly or maliciously - you just get those rules from multiple sources and VERIFY THE CHAIN FOR YOURSELF. with PoW you get objective measure to compare those chains, with PoS you get nothing.

> With PoS, you do you have a somewhat similar option: you can measure the market value of the coins of each chain.

no, you completely misunderstand the problem at hand. given coin X and multiple chains of coin X - how do you compare those chains?

market price of coin X tells you nothing how to distinguish between competing chains. market price is completely detached from actual verification work happening on chain.

Only in the presence of a Reserve Bank, which Bitcoin doesn't have. There's no ability for any authority to increase the number of Bitcoins possible, which means it's permanently deflationary.

Inflationary currencies pay interest via Reserve Bank policies in order to be managed. Bitcoin has no such mechanisms, nor can any be implemented.

> The reason people would join such a system is because they want to get wealthy too!

Which is why ICOs are so popular. Why pay tribute to the original Bitcoin miners when you can just become you're own, recognizing that the only thing holding up the value is irrational in the first place (doesn't mean it's not a real way to get people to part with their money).

> The thing they spend their money on is more useful than the money itself.

Computers are one good in many-faceted economy. Deflationary currency means the currency is worth more against everything in the economy with each passing day. So not only will I not buy a computer with it, I will also not put it in a bank (why risk it?), not buy stocks, bonds, or even really loan it to anyone. In fact the right thing to do (if there was anything pinning it's value) would be to first spend all my non-Bitcoin money on necessities, and acquire and sit on, in offline wallets, as much Bitcoin as possible. But Bitcoin is a currency - to even be useful people have to actually use it.

So why don't people do this? For the aforementioned reasons - no one can actually require me to hold Bitcoin to pay taxes or extinguish debts. So just sitting on it is foolish since there's no real way to predict when the irrational market will end - except over the long term, I do know the price must crash since every Bitcoin market participant must eventually cash-out to pay taxes and electricity bills and what have you. So in fact there's nothing holding it up. The only actual reason anyone has to hold Bitcoins is when they get ramsomware'd.

In fact it's worse then that - since the value of early Bitcoins is less then the value of later Bitcoins, but all Bitcoins are going up in buying power, the electricity company is eventually the richest entity in Bitcoin without even having to be malevolent.

Of course, this doesn't happen because none of them can pay their taxes (or their suppliers taxes) in Bitcoin. In fact no one using Bitcoin can - everyone eventually has to sell all their Bitcoins to someone to recover the currency they need to do that. But who's buying it then? There's a finite amount - if it stays in use it's worth more then you sold it for when you try to get it back - or, since everyone eventually has to sell it, it's worth less - and less again.