It's been nearly ten years since I watched with any regularity but once upon a time I did fit that description. There's a lot of reasons that went into why I watched.
1. Humor. I can't speak for anyone who would take this stuff all that seriously in this day and age. But there were some guys who could crack me up on the mic back then. What was usually the source of the most laughs were the guys who really tried to pull off serious emotions out there, along with horrible wrestlers who could be counted on to botch things in the ring. (Well, except for the ones where they blew things and people got hurt. I'm not sadistic.)
2. Nostalgia. There are entire TV networks built around providing this to its audience. It was nice to be able to sit back and be reminded of a time where the most important thing in my mind was whether the Hart Foundation would be able to beat the Nasty Boys (They weren't. ing Jimmy Hart.) Towards that I know as a college student it was nice to have a couple hours a week set aside where I could put my brain into neutral and just relax. It's the same principle that makes shows like Jersey Shore, Big Brother, and the various Real Housewives shows. Not every piece of entertainment needs to challenge you. In fact it's for the best that some of it doesn't even try.
3. Respect for the craft. When I was 15, about the time I probably should have outgrown the whole thing altogether, I read Have a Nice Day by Mick Foley. I encourage anyone to read it. It's a quick and entertaining read even if you don't give a about wrestling. And if you have any interest in the subject at all it's a nice chronicle of how the game changed from the 80s heading into the new millennium, as well as covering the parts of it that will probably never change at all. As a guy who was doing high school theater at the time it gave me a new layer of appreciation for all the work that goes in to making it happen at the highest levels, from production to the actual in ring work. The live, no off-season, show must go on aspect of it all was intriguing. And I can think of a lot of things I would rather do than watch a soccer match, but even then it's just about impossible not to have immense respect for the years, even decades of work that it takes those guys to get to where they are.
Ultimately for me it got to the point where it was too repe ive week in and week out to bother carving out two hours of free time that was increasingly at a premium as I grew up. I won't begrudge anyone who just can't get into it, or see past the most cartoonish aspects of it (and there are many of those), but I wouldn't immediately assume that anyone who watches it must be brain damaged either.