They ask you to become their banker? you need to play smart for creating a contract and ask them to accept it, if they don't want to accept it, don't be their banker. You can make a contract if you will get 10% profit commission if they want to sold their coins or anything that you will have an advantages.
It's not that easy for protect their holdings, you will take a risk to make sure you hold in a safest place, not lose the seeds phrase, etc.
The question is not so much whether to keep their funds or not. The question is how to really get them interested in bitcoin so that they learn to manage it themselves.
No I don't want to take a commission, I am not a banker. It's not my job. I'd rather they learn what bitcoin is for.
That is a good approach, one of the main things with Bitcoin is obviously self custody of that
wealth/Bitcoin and not to trust/involve any third party.
Its a tough one trying to teach people
I have had mixed results, I find the ones who already have an appetite to discover an alternative
to the FIAT system get interested in Bitcoin and those who dont care or who dont see a problem
with it dont have a need to become involved with Bitcoin.
Eventhough the vast majority of people are only interested in what is in it for themselves I try to
educate potential Bitcoiners on the merits of Bitcoin other than the "Investing" topic, put X in and
get Y in return, there is way way more to Bitcoin than that.