I don't understand why so many people are so pessimistic about $ETH .

Looking at the entire crypto market, the only ones that can still let you sleep peacefully in extreme situations are $BTC and $ETH , the third one basically doesn't exist.
BTC represents consensus and underlying trust, ETH represents technology and application ecosystem. You don't need to bet on the direction, just on whether the entire industry can survive.
If one day Ethereum is truly eliminated by the times, the conclusion will be very clear: it's not a failure of a certain project, but that the "technology-driven crypto system" path is no longer feasible. By then, Bitcoin might still survive as a special asset, but other so-called crypto assets will most likely all go to zero together.