Reading through the thread it really struck me that everyone is dishing out advice like I. Business or life there is a text book to follow.
It is easier to tell your friends dad which investment he can diversify into but you forget that there are factors like your friends dad interests, you friends dad capital or even the potentials of other businesses doing well.

What happened to your friend is a tragedy but this doesn't mean he wasn't smart. You can Invest in food, or other businesses and it ends by closing it up. When tragedy happens like this that is where you reserve comes it to help you stand, and the big mistake I see here is not getting insurance on the property. Let people do what they feel ok to do, investment is not about the amount you can handle but how well and effective is it for you.