The reason is that bitcoin is the first crypto money in the world and the total bitcoin supply is very small. And i think bitcoin not useless. Yes, the transaction speed is unfortunately slow compared to the new coins, but it is not very accurate to only evaluate the bitcoin from the speed of the transaction.
Carefull with your words bro, i think you didnt experienced yet the opportunity and money that can bitcoin give. If you just started today in investing in bitcoin you should understand that 2018 is not the year of bitcoin,.maybe next year of next next year.