If I have a client that wants to invest in Bitcoin or any other cryptocurrencies, but he/she does not have any actue ideas on how the Bitcoin ecosystem works. How do I convince such person?
You never convince anyone to invest in Bitcoin. If there is a knowledge gap, you can supply them with basic knowledge that can help fill that gap and enable them make an informed decision themselves.
Convincing someone isn't a good idea when its comes to investment or anything that involves money because something might go wrong and then you will be held accountable for it. So it is best you just create an awareness in whatever form and allow your client or whoever to make his/her decision either to invest or not.
What is needed first is to get a proper knowledge first before telling someone about it, making research and asking questions and also reading can be of great help to know more about bitcoin investment.