Organizations like fraternities commonly have Halo or CoD tournaments for profit. I was in a fraternity that did multiple for-profit Halo tournaments on campus as a fund raiser to help us pay our bills. I don't think we ever did League of Legends though.
The legality may be different, but Meltdown E-Sports operates e-sports bars in cities across Europe where League of Legends tournaments and leagues are commonly held. Meltdown events aren't directly for-profit (they don't make as much money from entry fees as they pay out in prizes), but since they occur at Meltdown e-sports bars where the players and viewers purchase drinks and food, Meltdown makes a lot of money from them. The events are just a tactic for Meltdown to get people in the door so they can buy (highly profitable) alcoholic beverages.
It may also be similar to unsanctioned Magic: The Gathering tournaments done by game shops.