I've had 3 LED fixtures burn out in the last year. They are all 3 years old or younger. (warranty is for 2 years) We have to replace the entire fixture because the bulbs are not replaceable. It's extremely inconvenient, especially trying to find a fixture that matches since they change style every year. (found them, but that was not time well spent)
The 40w bulb I've had since I was a teenager has lasted decades and shows no sign of decay. Trying to remember the last time I replaced an incandescent. Maybe 8 years... no, it was 12 years ago. The only reason we don't have all incandescent is they produce too much heat for our climate and we use LED where we don't want extra warmth.
But we have inconstant electricity here, so electronics (things with chips) die much sooner than older style electrics. Even still, 75 years seems like an underestimate. He must have a lot of light fixtures and turn them on and off frequently to go through that many bulbs.
I don't quite have 3,500, but I did start stacking them back in 2007-8 when whoever was in charge then first announced their plans to ban incandescents. They were super-cheap prior to say, 2020, like $1 a four pack. I have enough for at least 40 years, possibly longer, in all wattages and sizes. I was joking with a friend, who said, "You should brag about that on your dating profile!" 😆
To Jordan's point, you can still order incandescents as red tinted heater elements on amazon (for warming birds and other animals). I was able to find 50w, 75w and 100w bulbs. Red filters are better for nighttime use anyway!