No, not a joke at all. Millions of people around the world tune in to watch the massive boxing matches even if they don't follow the sport. Many of my friends will go out on a night a big boxing match is on just to watch it in a pub instead of paying for it on PPV. Floyd "Money" Mayweather is massive, especially in the US. Plus the fighting sports seem to be very popular with the females as well, they seem to get a kick out of watching ripped sweaty men kicking 7 shades of **** out of one another.
There's also the likes of Lebron James and Kobe Bryant as basketball is huge over there. I've never watched a basketball game in my life yet I've heard of these two.