Regarding altcoins - the big difference between 2021 and 2025, is that in 2021 there were about 270,000 different altcoins. Now there are over 3 million types of alts, many with inflationary supply.

That means the global supply of alts is increasing faster than the global supply of fiat across all national currencies. That's why alt prices are depressed.

A lot of alts need to die and be delisted. But am not sure how such a clear out would happen.