You are in the right, do not back down from this idea, it is core.
More important than picking a field is understanding that things change, that your job today is very likely to be totally different even 5 years from now. If you let yourself get complacent or stagnant, then you have a big problem.
More important than picking a field is understanding that things change, that your job today is very likely to be totally different even 5 years from now. If you let yourself get complacent or stagnant, then you have a big problem. I'd even take it a step further, if your job today is the same as it was 5 years ago, big problems are on your doorstep right now. Change is the only constant in life, and that applies to work as much as anywhere else.
Always push to learn something new, take (smart) chances, and either set, or be at the top of the learning curve. That approach will make you be make mistakes more often than if you stay stagnant, but the payoffs are always better.