Eat! Have fun-raisers for scholarhips and charities, eat, attend business meetings, eat, learn to pretend that you're not planning to take over the world; eat, drive funny little cars . . . oh, wait! That's the Shriners; eat, do the dishes, . . .
Why do people want to join? So you can attend the annual BBQ, of course!
Seriously, though, people want to be Masons so they can learn the secrets of building better temples.
Great answer!
I know that some actually have a good enough understanding to initially petition the Lodge for that very reason, but many others only learn it as a part of the instruction that they receive during their journey through the degrees.
I have witnessed a lot of men joining because of their desire to simply belong to a fraternity, and discover the TRUE meaning along the way.