It's not a matter of how long they may last. It's a matter of how many shots they last.
A guy that shoots 200 shots a month may have a scope last many years . A guy shooting 200 shots a day will scramble most scopes fairly rapidly.
I hear guys say "I've had my scope 2 years with no problems". That indicates to me they don't shoot many shots. A scope sitting in the corner wears out very slowly. So how long you have had it is not really an indicator of longevity. How many shots you've put on it is.
I'm happy to get 6-8k shots on an airgun scope. The lifetime warranty has been used on every airgun scope I've ever bought. Not one scope has ever lasted over a year. MUCH less on the rifles I shoot regularly.
Iron sights will serve you well at airgun ranges and last forever. If you shoot regularly and use a scope plan on spending $400 for one that will last. Also plan on sending it back periodically for warranty service. A spring gun will eat the best of them sooner or later. Sooner if you plan on shooting it daily.
Many air rifles (including the expensive ones) have alignment problems that require adjustable mounts or barrel bending to get them to hit optical center. They will fail sooner if zero requires a lot of adjustment.
Big objectives mounted high gather more shock from recoil and fail sooner. Heavy scopes with lots of gadgetry fail sooner.
There are a lot of things to consider in the longevity of a scope. Even the very best optics will fail if they are a big scope mounted high and zeroed way off center.
A small, light scope mounted low and zeroed close to the center will last many shots on a mild spring rifle. It will give you many more shots between warranty repairs. Still expect to have to deal with scope problems if you shoot your air rifle a lot.