The stupidity of wanting to grow up

We all want to grow up. We're desperate to get there, to grab all the opportunities we can...to live. We're so busy trying to get out of that nest, we don't think about the fact that it's going to be cold out there... Really freaking cold. Because growing up sometimes means leaving people behind. And by the time we stand on our own feet...we're standing there alone. So why is it we want to grow up so fast?