If it took 1 person to make, sell, and distribute those things, then $70 million are enough to retire comfortably. If it takes 100 people, then you could still retire, if you lived somewhere cheap.

More realistically, you might sell a few hundred thousand to the developed world, and then sales fall off a cliff, because it takes a lot of work to distribute outside your home market. Total payoff: Less than 2 months' salary.

That's the concern with the new lights. The industry is built on 1,000-hour bulbs and regular replacements. We currently have a boom as incandescents get replaced by fluorescents and fluorescents get replaced by LEDs (my father hates fluorescent light). Once that is done, who is going to buy bulbs at the rate that the factories can produce them?