It's great that you've gotten people interested in investing by teaching them about Bitcoin. However, since you understand your friend so well about Bitcoin, your friend is particularly interested in investing in Bitcoin. But of course you need to warn them about this before investing in the Bitcoin market. They need to be made aware of the risks involved in investing when the Bitcoin market is volatile at times. Make sure you are well-informed about all aspects and then give advice for Bitcoin investment. If you don't tell him about the volatility of the Bitcoin market, he could be particularly vulnerable. So I think it's best to invest in Bitcoin later after understanding that the investment will be successful and profitable.