If you ride your bike a lot, and some point the bearing races in the hubs will wear out and you'll need new hubs, same for the bottom bracket, the rims will either get ground down by the brakes or get a dent that requires them to be replaced, fenders will get bent and / or rust off, screws corrode, brake / shifter cables need to be replaced every few years...

Bikes that get ridden a lot are like the ship of Theseus...