Although I believe the number of people who truly want to become pro anglers is much lower than the number of those who say they want to become pro anglers, I think they want to do so for the same reason someone chooses to become a pro golfer, bull rider, or bridge player. They love it.
Define "rewarding".
Being a trauma surgeon likely is not fun either, lots of hours, lots of stress, probably isnt easy making so many decisions that change lives daily.
I guess my point is that everything is relative. Not everyone wants to be a truck driver, teacher, doctor, lawyer, or cop. That being said, being a pro angler without side income or sponsorship revenue is an unsustainable strategy in the long run.