Of course the single thing that makes them last the very longest is also the simplest - just like most electronics - never turn them off!
Very true but most persons wouldn’t believe it. Start up puts the most stress on anything electrical.
Some devices will last longer if they're never turned on (some other devices will fail prematurely if they go too long without being turned on).
More to the point, if a 100-watt light bulb in a closet is used an average of 5 minutes per day (hardly an unusual situation) such a bulb will use one kWH every 120 days. At $0.10/kWH, that would be $0.30/year. Even if one could replace the light with a magical perfect light bulb which provided just as nice light, used zero energy, and never wore out, such a magical light bulb would in absolute practical terms not be much of an improvement over an old-fashioned incandescent. If the new improved light bulb cost $5, it would take 13 years to pay for itself, even ignoring the opportunity cost of the capital.