I believe that they're popular mainly because well it was the first of all cryptocurrencies to be made. Honestly most of the other coins are scams and greedy ways that the developers make money. The only other coin I can think of that isn't a scam are dogecoins! What do you think?
because for me Bitcoin has already shown why this is the most popular cryptocurrency) For example, it is how much we have improved our world especially financial transactions for the last decades. Think that "new politic of cryptocurrency" will only make more strong the countries with developed economy.