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?
Bitcoin is the most popular of all the digital currencies because it is the first of them all. Without bitcoin, I don't think that there will be an emerging digital currency. Also, as the first and original digital currency, it has the highest price of them all, so the tedency of the users are to be attracted to it because it has the most price.
in cryptocurrency transaction very fast and more secure and the price of btc is growing up day by day.