Earlier quoted context omitted.
It's about internalizing the idea that it's a feasible choice you give actual thought to.
How to distinguish between "I didn't know that was a feasible choice for me" and "I know what programming is like and I don't want to do that as a career"? How many girls and women fall into each category?
Now that "tech" is so important and lucrative I'm sure this is changing to some extent, but this is a recent trend that's probably 5 years old at most. Tech wasn't viewed the same as it was now in 2012-2014 and felt like a much more risky and inaccessible field. Now it looks a lot more like any other high paying corporate job.