As a drummer who has gigged and recorded extensively for close to 40 years - I can answer the original question with a very qualified.....it depends!!!
Cheap cymbals will not last long at all (in fact they normally sound like crap to start with - so the sooner they die the better). Good cymbals can last for decades (even thin cymbals)...but the tone will eventually lose some of it's bite - from both a combination of repeated impact and the dirt, sweat, smoke, etc. that eventually accumulates (which depending on the musical application, may not be a bad thing). As someone already pointed out, if you beat on something long enough, it will dull if not break.
I agree that often the older "vintage" cymbals may indeed still be in one piece because jazz/big band drummer did not abuse cymbals - that's not to say that they did not play loud (try to compete with a dozen horns - with no drum mic'ing) - but rather, they knew the comrrect way to hit.
I must completely disagree with any drummer that contends that it is normal or expected that cymbals will break. I've played about 3,500 gigs in every conceivable genre of music. I've rocked big time trying to compete with guitarists with double stacks of marshalls, etc. - and I've had to swing loud behind large horn sections - and I have never, never broken a cymbal. A drummer can get significant volume and sound projection with proper technique