I think elementary and middle schools do a better job teaching math than high schools and colleges. Even though they do teach abstractions, it is possible to visualize what those abstractions are --that is until at some point when the subject of Algebra gets going. That's when some kids decide they're going to do something else.
From that point on, more and more kids get flummoxed. Some are lost when learning Geometry, even more are lost during Algebra II, and by the time they take Trigonometry/Pre-Calculus, many have learned to plug and chug. I'm watching my middle school and two high school kids go through this. It is not a pretty sight. By the time they're picking out courses for college, most of those headed for some kind of STEM studies have figured out coping mechanisms.
We encourage kids to explore the STEM subjects, but then they have to deal with learning everything backwards. And we wonder why so many of those who study STEM are skewed toward introversion. It's because only introverts can devote the mental bandwidth needed to overcome the extraordinary effort of integrating abstractions into their understanding, and then remembering it well enough for it to be useful later on.
Let's face the reality: this is not an "Engineering" thing. It is a mad rush to abstract concepts before they're even understood. Those who get it, don't seem to understand what all the fuss is about. I made a deliberate effort to remember my frustrations and what it felt like while trying to learn this stuff. I knew that eventually I would understand this stuff and then I'd look back and wonder what the confusion was about. I try to remember that confusion and what triggered it so that I could help others get past those problems.
Despite my grousing about how we teach this subject, I do appreciate a wide variety of mathematics. It is a truly a thing of beauty. But the frustration of learning it is not something I'm likely to forget. I've seen math teachers in many different school systems. I've yet to meet one who inspired even a small fraction of the students in a class.
If we were to change one thing to encourage more kids to embrace the STEM fields, it would have to be to find a better way to convey and teach Mathematical concepts.