I am quite sure you might have invested in some wrong altcoins in the past which did not made you have immense profits. If you would have chosen a correct altcoin then you might have at least doubled your investment by the time. Investing in bitcoins is wise but you need larger amount of funds in order to make extreme profits in smaller intervals.

The price for bitcoins is on the top of each altcoin so if you are investing in smaller amounts than bitcoin would only give you smaller profits no matter how much the price changes. But, imagine you invest in smaller amount coins like XRP, Doge, etc and the price for those coins doubles, you would certainly have huge larger profits as compared to bitcoins. What I want to say here, is investing in bitcoin as well as altcoin can be profitable for you if you choose your altcoin carefully.