Partly because Fortnite is the new hotness and because League has existed for like 9 years.
Partly because there is or was a Fortnite tournament recently and there's still hype from that going. Same thing happens with league during the LCS
what kind of losers like to watch someone else play a game they could be playing themselves
[sg-lux-2]
its almost like people enjoy playing league more than watching it since it doesnt have much appeal to match and isnt aimed at children while fortnite in most cases is better to watch than to play, being focused at children which is why the twitch chat and youtube comments on nearly everyone of their channels is just filled with children, along with the game still being relatively new so people are more interested in it. and one final thing a new season for the game is out which brings more attention then normal
league is dying, and RIOT is not going to save it