I think the line between casual fans and what ever you call fanatics...Saddos i suppose is one people are a bit too quick to draw. The time you can devote to following any sport is going to fluctuate and with that your knowledge and love of current fighters with it. Unless you start young as a fighter yourself then most people will have started as casual fans and like you say casual fans keep the sport going. Those PPV's and ticket sales made by casuals do a lot to keep promoters, managers and fighters going (even lower down the card) when a lot of hardcore fans (myself included) may be content to watch the exact same fight the next day or on a free platform.

The closest analogy i can think of is Football or what the Americans would call Soccer. That has been largely ruined by casuals who in their millions will claim to support a team not even in their own country when the football league itself will have teams with thousands of loyal supporters who actually attend the games going under because they simply can not compete with foreign owned franchised playthings of the Premiership.

Yes Lomanchenko is not suddenly a has been because of one result, and the same annoying casuals will always be first to offer their opinions when big heavyweight fights or other fights that are 'events' in themselves are televised. But what are you going to do? However annoying they are, you can't just dump your family out on the street mid fight