Greed is the most common reason why such people fail from their investments because they cannot focus on setting plans and actions for the investment to succeed, but rather they resort in thinking that it can make them rich quickly so they should put a huge amount to gain huge returns too, which I think wont be possible if they dont know well their investments in the first place. With this, your friend has clearly believe on crypto as a get-quick-rich scheme thats why his actions are all based on greed and the desire to be fully profitable in the end.
Well, in that case, his friend will only not lose his money but might also lose their trust in each other. He was supposed to listen to what OP said to him for he has experience in the market but if he pushed his decision to put all of his money into his investment, I couldn't think if OP has any interest in helping him anymore. I'd see his confidence in crypto but having such a decision is not advisable and too risky.