Assuming that you see bitcoin as commodity the answer is obvious. Any amount of bitcoin is enough like as with gold metrics (carats, ounces). As we know there are many people in earth without gold but nobody wander if gold reserves are enough compared to world population. Moreover assuming that you use bitcoin as currency again I could say that is enough too. Even for 1 satoshi (10^-8 btc) if the need arises for less then you can convert it into fiat or an altcoin.