The first thing you need to let him know is that he need patient, without it he wouldn't be any profit because right now, if you want to make money holding Bitcoin, you need commitment and dedication without shaking when the price is doing his things, the Bitcoin market is so large that it will need time before your client can be profitable, I hope he is ready to hold and be a diamond hand no matter what happen. This is important for him so you don't get too much complain from him.
Another suggestion is let him be their while helping him buy Bitcoin, so he can learn against next time. I had this guy that was on my neck any time he want to buy any coin, luckily for him he didn't buy Bitcoin but another coin and he profited quickly due to the nature of altcoins and all of a sudden, he start coming with different phone to help him buy coin for some of his colleagues and he didn't know how to do simple but and sell. I thought him this time and I never saw his traces again.
I totally agree with you. When investing in Bitcoin it is crucial to be patient and committed for long term. Market can be unpredictable and profits take time. OP client needs to understand that holding Bitcoin requires dedication and perseverance through price ups and downs. By setting clear expectations he can avoid misunderstandings. Involving client in buying process is also great way to teach them and prepare them for future investments. His experience with eager investor shows how hands on learning can build confidence and independence. By teaching the basics he has helped them and freed himself from repeated requests. His approach is a great way to support clients in their cryptocurrency journey.