Get him to decide for himself.
Why should you feel the obligation to recommend an investment strategy to someone else entirely? If it doesn't pan out, they will blame you and your reputation is on the line.
Especially with the crypto market at such heights, I would be pretty uncomfortable in terms of selling recommendations to anyone. If you absolutely want to, either tell them to DCA or to wait until a correction below $40k occurs again before buying a lump sum.
They will certainly blame you if you're the one who's been encouraging them to invest.
But if it's your friend that asks for a help then you're not accountable for whatever is the outcome of his investment through bitcoin. But it is bitcoin and it's understandable that it's best for long term.
Still, there's a need to explain how high its volatile is.
yes, I would also probably do the same. I will explain what I know about bitcoin or cryptocurrency, then I will give the final decision to him. many people blame others when they get lost in the crypto world because of such an invitation. even though there is currently so much positive news regarding bitcoin or other cryptocurrencies, we can't stop FUD which usually comes suddenly and dumps prices again. however, give him as much explanation as possible, and give him references to charts and news. maybe you can explain to him about the popular coins in CMC or CG, it's very easy to understand. other than that, try to give him an idea about the potential of a coin, and you can give him a reference in graphic analysis that is usually found in online magazines such as Cointelegraph.
again, let him decide whether he should buy or wait. make sure to tell him DWYOR