We should not confuse the economic meaning of rational with a psychological one. Consumers are rational in that they have a goal, and their actions are taken to meet that goal given the information they have, their preferences, priorities, etc. Buying incandescent lightbulbs is perfectly rational, economically speaking. The consumer wants a light bulb. They look at the selection, see the price, and weigh the merits of each choice. They then select one. If they don't choose the flourescent one, they are not irrational, but rather they have a preference based on price, brighness, etc., and/or lacking information about flourescent lightbulbs. Nothing economically irrational about that.

That does not mean that these people aren't dumb. They may or may not be. That has no bearing on their rationality.