While I generally agree, there are a few exceptions.

Ethereum exists because Bitcoin isn't capable of running complex scripts.

Monero exists because Bitcoin is too transparent.

And the vast majority of people "investing" in it have no concept of the underlying tech/utility/scalability/whatever, they only care "token go up!" and essentially treat it as a penny stock.

It'll eventually tank, but not until the insane FOMO ends. For example, the completely useless Dogecoin still has a $600M "market cap", and at one point popped over $2B.

Absolutely all of them? You may want to look for some subtlety. There are coins with a specific purpose, for example Monero, that have a clear purpose which is separate from Bitcoin.

>All the alt-coins exist only because BTC got too expensive and they wanted in

Ethereum was explicitly created because Bitcoin doesn't support decentralized applications or really anything beyond sending tokens between humans. Vitalik tried to work on the Bitcoin codebase but was shunned and was forced to start a new project.

>There are all pyramid schemes

Do you include ethereum here? if so you are woefully misinformed.