> Some engineers deemed 1,000 hours a reasonable figure to balance the various operational aspects of an incandescent bulb, since longer lifespan means reduced efficacy (lumens per watt): a longer-life bulb of a given wattage puts out less light (and therefore proportionally more heat) than a shorter-life bulb of the same wattage. Nevertheless, long-life incandescent bulbs were and are available with lifespan ratings up to 2,500 hours, and these do in fact produce less light per watt.
What I was trying to say in my previous comment was that while there was a cartel which did reduce the lifetime of commonly-used light bulbs, they didn't do it solely to increase their profits - there was an actual technical tradeoff involved, and they chose a figure which provided (in their opinion) a good balance of all the involved parameters. That's what always gets forgotten when this story is mentioned.