I pulled 10% out of my ass. It was in the midst of my grilling for the CIO job I didn't apply. Haha. I think 10% is about right though. Likely enough to insure the purchasing power of the initial investment is preserved and grows if he lives many years into the future but is small enough that if he has an adverse health outcome in the next few years and needs liquidity he doesn't have to sell his Bitcoin in the midst of a bear market to pay for care his daughter can't provide.