It doesn't matter whether or not the coins/tokens you want to invest in is in top 100 or not. The risk is there even if you buy those that are in top 10. You also need to note that somehow they are interconnected to each other in a sense that when BTC is on a bearish state most probably the alts will also decline. Though maybe not all the time but the rate of this phenomenon is high. But to ease your mind just a little, yeah I think the chances of loss is higher especially if the alts you're thinking of isn't supported by more people. Remember that it is the demand and supply game.