You are correct that bitcoin will stay on the top triumpant. Even with the fall of the cryptocurrency market bitcoin manages to survive and stay on top.  Yet everyday new coins are coming in trying to get into the crowded space of cryptocurrency. And so competition is getting rough. Though until now none had ever dethroned bitcoin, but the sales could have gone up if none of these coins existed to create a competition. Of course they are made for a special purpose and hence it is impossible not to get customers for them to have sales.