I've never worn out a good road bike tire. Cuts from road debris always trash the tire first. But I've gotten within a few hundred miles of wearing out a couple of lightweight tires -- Schwalbe One V-Guards -- although cuts killed those tires first. Hazards of riding rural areas near roadhouse bars and stripper clubs. Liquored up rednecks peel out of parking lots tossing glass bottles everywhere. And more recently there's new McMansion housing developments with lots of unsecured debris falling off trucks and trailers. Razor sharp chips of broken slate flooring material sliced up a couple of tires that might have lasted another few hundred miles.
Recently I had to retire a Continental Grand Prix Classic skinwall due to cuts -- I think it was metal braces from roofing or framing material scattered completely across an intersection after a collision. Happened at night and by the time I saw the debris it was too late to stop, and there was no clear path anywhere across that intersection. That tire looked like it had another 200-500 miles on it, estimating from the Conti wear dimple depth. That GP Classic has a raised center tread that gives it more wear life compared with other Conti road tires. I think that tire had more than 2,000 miles on it by then, not bad for a reasonably lightweight, smooth rolling tire.
And the puncture resistant, thick rubber tires on my hybrid and errand bike will never wear out in my lifetime. Those tires might develop age related crackling after a few years. Depends on environmental factors -- exposure to sunlight, ozone, etc. -- although my bikes are stored indoors away from premature aging conditions.