it's made to!
breaks every so often may be good for the longevity (if there is heat buildup), but from what Ive experienced, heard, and read, and seen, turning a fan on and off a lot causes more damage than running it for a long period of time.
Oh and when it eventually dies, its not going to be sudden, it will be gradual and obvious. That was a big concern i used to have - that it would suddenly die without warning