Well I'm guessing that Ghettos fan sees 5000 rpm more often than the average grocery getter.
If the fan is constantly freewheeling (like when it cold out!) the small bearing that supports the entire assembly (which weighs at least 5 pds offset from the pump itself) is stressed to the max, I've had three come apart on me over the years from abuse. Last one was on my 84 Bronco II and nearly left me stranded on the highway as a result, luckily it was threaded on the pump snout and I could remove it easily and make it home. That vehicle was no high rpm power monster either, but I drove it hard because it was so underpowered and the abuse eventually killed the fan clutch bearing.
If you like, take the fan apart and replace the bearing with one designed for snowmobiles (packed with synthetic grease), it will last a little longer but with all that weight hanging and spinning offset from the pump snout they just don't handle abuse well. For the Bronco I just reused the mounting shaft and welded on a bolt on mounting plate for a stainless flex fan, I found that having less weight hanging off the water pump made them last longer too.
I put on a lot of miles on this truck in this configuration and during winter would remove the fan since the truck didn't need it anyway. I'm sure I'm not the only one who has had poor luck running a clutch fan on heavy duty vehicles.