People do what they want to.
Personally, I like to agonize over my choices first, and then go ahead and do what I wanted to do in the first place. I reason, and frustrate my rationale, and look at every situation with excruciating objectivity, and when its all said and done - find a way to rationalize my desire.
If I'd been Eve in the garden, the world would have fallen 10 minutes faster, and I would have managed to somehow walk away feeling justified.
Why does desire beat out reason? Maybe because reasoning is for computers. Maybe we yield to our hearts because it makes the human experience worthwhile. Maybe we just wish we were smart enough to care about consequences, but the truth is we're just not that evolved as a species yet.
Maybe we're not always supposed to do the smart thing. Maybe smart is overrated. Maybe we take ourselves too seriously. Maybe life is more about defining your heart in time and space, than it is about navigating the world efficiently and with expert precision.
Whatever. I don't know how we get to our choices, or why we ignore our reason on the way there. But here's what I do know: If you're going to make the leap, make the leap. Don't kindof decide to be silly. Just embrace it: We are human. We are ridiculous.
We are only more ridiculous when we agonize over our happiness. If you're gonna crash and burn, at least enjoy the ride. Otherwise - just stay out of the car... and relish how intelligent and advanced you are compared to the rest of your joy-riding, crash-test-dummy-esque species.
In the style of those old Choose Your Own Adventure books --I leave it to you, O Internet.