For most of us the ultimate goal throughout our entire school and university life is to get a good career with a six-figure salary. But as the years go by, you realize that you're good at what you do but you just keep doing the same thing over and over again like a small cog in a big fat money wheel.
I don't believe that girls are turned off by STEM because it's hard or simply because girls think they're bad at math. Girls aren't wimps or wilting flowers; they don't shrink from challenges just because something isn't a strength. We, as a culture, just aren't doing a very good job of selling tech to girls.