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.
As someone who went all in (100% of my portfolio, I still had a 10% of my money to cover unforseen expenses) I can confirm it is crazy, it is risky but weeks of being 90% down are long gone. I started taking out my initial fiat investment every year since and I still have over half my coins.
People should take calculated risks.
You're right there though i can't say that putting most of your money in btc would be a highly calculated risk. I think around 40-50% would already be high enough and i don't want to compromise my expenses for that kind of risk.