Color wheels are subject to failure at any given moment, but typically after 4-5 years of average service. YMMV, as Mitsubishi tend to last longer, Toshiba shorter, Samsung is a random crapshoot.
Teeny tiny electric motor made from thin metal and plastic, turning at 10000 rpm, crammed into a tight space 3cm from a 390-degree high intensity lamp throwing off UV rays and enough light to be seen from orbit (exaggerated that last bit, but you get the jist).
They get wobbly, they groan, they seize, they detonate into shards of plastic confetti. You slap in a new one and move on. C'est la vie.