I've killed 4 with potholes/rocks (Wolber GTX, Sun CR18, Sun Zero Degree Lite, Araya something), had one brake surface crack and bulge out (Sun Zero Degree Lite), had one Mavic 192 fail at the seam, have some cracks developing around spoke holes in one of my Nisi Contachs. Worn several brake tracks down to concave before replacing.
Unfortunately I've never tracked mileage on any of my rims. I had a collection of rims hanging in the garage that I'd intended to recycle but I just left them hanging in the garage when I moved out of that house. I was just going to put them in the curbside recycling bin and see if they'd take them but never got around to it.
Here's a dented rim of unknown make/model. Some kinda RM-20 clone. I'm still going to ride it for a while. Must be about 300 miles on since the dent.
Dented rim by
Lester Of Puppets, on Flickr
Mavic 192 - blew out while airing up to 110 psi.
PB100029 by
Lester Of Puppets, on Flickr