Well, that is something i likewise do; i know there might be some good Altcoins/tokens but finding them is like looking for a needle in a haystack, thus that sort of investment now becomes more like a gamble, and that's not something i want to do. Having said that, some Altcoiners might come up with the argument that Bitcoin is also risky, which is true, but Bitcoin has an actual utility as well, thus you can be pretty certain that it isn't going extinct, neither will it just disappear like some altcoins would, it will plunge in price as it usually does, but the price will definitely appreciate again. It is a perfect decision to stick to only Bitcoin if you can.