All in? HELL NO, nobody should go all in, regardless of age. Taking higher risks when younger--that's all well and good. But going all-in on anything crypto is a recipe for bankruptcy. I wouldn't even allocate 20% to crypto. You'd have to be crazy to go even half-in, and I say that as a person who likes bitcoin. A lot. It's just way too risky.
Definitely agreed, even as an extremely faithful to BTC, I would not have even the slightest courage to go all in on BTC, atleast not in the current market volatility. It needs to be extremely stable to even "kind of promise" a good return for someone to go all in. I would recommend allocating maybe 10% or even 15% to BTC but "all in" is an extremely high and absurd for the normal people of today.