There will definitely be phases to enthusiasm, focus, and opportunities to shine (if you are continually learning).
The "young man" qualifier has various aspects other than 'ability'. For example, a young man may not care that he is a cost center as far as employer mother ship is concerned. He may not care that the work may be highly irregular in terms of hours. He may not care that he is asked to demonstrate rudimentary knowledge when looking for work. He may not care that ... but an "older man" will likely care.
You need to project a desired mid-life situation. Define the parameters, and then check out possible average programmer outcomes at mid-life, which vary quite widely.
Finally, the profession may look very different in a couple of decades (when you will hit your midlife). It certainly wasn't like this when I was your age. So I think if your concerns are general life fulfillment concerns, you should analyze and reach decisions in terms of generic knowledge worker situation. For example, your spending & saving habit choices will be far more significant factors than your choice of career if at 50 you need to do a re-eval or pivot what you do.