A DSLR body usually isn’t “used up” all at once. The main wear item is the mechanical shutter, which has a finite life and is often compared to a car’s mileage. Typical shutter life figures are commonly around 100,000 actuations, with some higher-end models rated for roughly 150,000–200,000.

So yes, photographers shooting thousands of frames per week can wear out a shutter relatively quickly. But for most amateurs, and even many pros, that takes quite a long time. Also, a worn shutter does not necessarily mean the whole camera must be replaced: the shutter can often be replaced for a reasonable service cost.

In practice, many photographers replace camera bodies before they truly wear out. The more common reason is upgrading for better image quality, autofocus, speed, low-light performance, video features, or other new technology—not because the camera suddenly becomes unusable.

If you’re evaluating a used DSLR, shutter count is an important indicator of wear.