I started seeing videos of his performance I think some time last year and he blew up this year. Not normally big enough for a headline but if they start promoting his sets, and people will see his Sphere shows, it will sell massively. Especially if there is a brand new main stage as I expect. It will essentially sell Sziget as an experience. Much like the Sphere itself that can host him for 8 shows in a row for 500 dollars per sear at a minimum.
If we get something like this at Sziget, but even bigger, flashier, it will sell out: