We have the confidence in our ability to learn, although the method we feel it will take, varies. Some have confidence in their ability to learn from books, some feel live instruction is needed too, others only feel confident with on the job training. But most say, I can do that.
The fly in the ointment is, what UT thought he knew about computers proved to be different from what he learned about them, but as soon as he felt he had learned, they changed... rapidly. We spend out professional lives catching up with ever more rapid changes. The changes in the building trades are amazing. Automobile mechanics have to understand electronics more than mechanicals. Even a burglar has had to learn about rapidly changing alarms and CCTV.
I know someone who wanted to be a nurse, healing the sick, caring for those who couldn't care for themselves, protecting the vulnerable from the bad stuff. A noble mission indeed.
Off to nursing school and discover, hey, it's science, bitch. What a shock. Not how to apply a cold compress to a fevered brow, but chemistry, biology, and things far from the delusional angel of mercy.