That sounds just about right, in my experience.
You must have installed them improperly or frames bb shell off, or maybe just terrible luck.
My thoughts as well. Even ordinary steel bearings should last 20 x that long.
I have CULT bearings (admittedly in wheels) that have seen the better part of 65.000 km. They're still like new and so they should. Cronitect steel as used for the races is it tough as it comes. Those bearings actually grind sand and other particles to dust without causing damage to themselves.
Those who seek ultimate low friction should try Krytox* loaded lubricants, it's even lower friction than the common PTFE particles.
Better still is Nanolubricant's ceramic grease which contains ceramic micro- (actually nano) spheres that reduce friction even further.
* Ideally you could use a water based chain wax with Krytox with added fine oil. The wax will seal the bearing better keeping the oil in, the oil will keep the wax in a soft state.