UFC has been popular since 2005 and has had a spot in the general sports world since at least 2010. Pulling a lot of viewers on New Year's Eve didn't make K-1 the colossus you think, but the UFC was worth 10 figures long before Conor, Ronda and UFC 200. K-1 was popular only (meaning that's the only place they could put on events and get any kind of serious interest) in Japan. UFC is popular in the USA and in some degree, a lot of the world. And unlike K-1, UFC gets people by the hundreds of thousands to pay for many of its events.
All those MMA fighters you listed are more famous than any kickboxing star from K-1.