People invent things because they have to!

People that invent things, look at the world with the constant thought of "Why the hell, does it work this way? Can I make it better?"
Usually, they cannot control themselves. Solutions start running through their mind and occasionally they will scribble something on a piece of paper or run a search in google to see if anyone found a solution already.

Though some will do it for the money, most do it as an impulse. Some inventive people I know would give their ideas and concepts to whoever can materialize them for free, just for the feeling of fulfillment