So far the comments are not understanding your point of view but i do.

The security online is a really tricky subject this days and they are paying you precisely for you to do all the learning and tests so they can be comfortable and just give the money they want to invest. I understand how VIP services work.

I personally don't think that you are on the wrong approach in that aspect since it's the nature of the service you provide, rich people moves different than everyone else and if they are not interested in learning about Bitcoin it's your responsibility to offer them a solution and you seem pretty good at it.

One thing you could do is when they have a determined amount of time(decided by your observations in their reactions with their assets inside Bitcoin or Ethereum) when they kinda notice how that kind of market work you could see if some of them is interested enough in learning and when the time comes, you can tell him/her that they can store a part of their coins inside a hardware wallet if they would like to use it for some transactions and one part for security.

They better know how unstable it is. The whole point of it is for any of them interested in learning more to do it. That is the kind of people with a lot of resources who can bring the market up.

That is just one idea for you to think about it. Your approach even when criticized is extremely good for Bitcoin's future and you better know that you're helping shape that future.