See if you believe in bitcoin and have not too much to invest further then single investment strategy is also best suited.You need to diversify your portfolio if you are holding a strong fund base and you could not afford to loose all of them in one go which protects your from the risks of loss and mental state.But if you are all in bitcoin (the amount you afford to loose is the first rule which you must know) then there is no worry.But the best you can do is to sell some portion at high prices and buy at dip again cashing out some extra profits.But there is one factor in crypto diversification which is selection of shitcoins by many which ruins their portfolio in first place rather than selecting some of the top alts.So if you are diversifying then choose the right ones to do or stick to btc only.