Bitcoin was the first cryptocurrency that became the most popular since 2012. It becomes more popular because of all the people or users believe in it and it was really great especially on how they handle the rise and falling of the market price. Cryptocurrency will surely continue its popularity since there where lot of fake issues concerning those currencies which gives them the chance to let people see how can they do and what strategies they do let people believe in those coins. Just like bitcoin and ethereum, they are already proven. Even Government not legalized cryptocurrencies but it will remain its popularity.
Bitcoin will definitely keep on being like that but do not get mistaken about all the other coins, they are looking mighty well too, even some governments are making sure that starting your own currency is not a problem, how?
If they are actually allowing bitcoin to be known and accepted and loved, then how could they stop you from making your own cryptocurrnecy? Of course there are rules about it, like how you can't just control it, you could make it, give yourself a bit, then you could end up not doing anything about it, just release it and let it be, let the community control it. That way you are getting richer off the work from the community, but you are not controlling it yourself which means that we are not going to end up seeing anything that is shady or illegal neither. This is why altcoins are going to be growing bigger and bigger as well.