This is why I always advice that anyone who intends to invest in bitcoin should have something else doing to pay his bills so he doesn't have to strain himself financially during the investment period. Your friend should deal with the situation because I sense betrayal coming from someone who didn't plan adequately before investing but chose to be a burden to others.
Like i said in OP, he earns in bitcoin so it's not like he is using money from any other source to invest, what he literally does is to sell some part of his earning in bitcoin whenever he receives his income and the amount he sells from bitcoin actually takes care of his primary needs and he is a core bitcoiner that all he does is to earn bitcoins. It's not like he doesn't plan to invest his money on other things but he is holding it for future benefits such that he can use part of his money to invest on real life projects and business maybe at a time when he feels he has made a lot of profits from his investment in bitcoin. He is not a burden to anyone just that his brothers are concerned that he is not doing well simply because he doesn't show off or own assets that will stand as proofs that he is making money from his earnings in bitcoin.