Diversification is what people do when they do not know what is happening.

As a case in point, if you put 1/100th of your bag into the top 100 coins, you might break even as 90% of them disappear, and bitcoin only 10x.

Diversification, in one asset type is just like gambling at roulette on black AND red at the same time. You are just going to lose. Especially over the long term.

Diversification over asset types is a way to hedge your bets.
Sure, most of your stuff is dollars (stocks, bonds, bank) but if all those go down, precious metals is a good hedge.