Well....Wasn't that the question?
And the point.....maybe its too big of a point or topic - I dunno...but...I think when a person enjoys something beyond a just a hobby or a pleasure & will go do it no matter the circumstance and chooses to be there 45-75hrs a week plus travel. Plus every minute there,you would rather be do nothing else and are smart good at it ---I'd bet the farm you can become wealthy and healthy at the same time!!
IF....He asked, could a casual hobby I do 5 hrs a week, maybe...make me enough money to sustain a living. That would not be even worth the "ponder" & I wouldn't be typing this right now.
Make no mistake I enjoy my property and my cars and all my toys... MY TIME. If Tomorrow I decided to start my own company and my wife said ...NOway --I never gonna eat fast food while you pursue a passion or a dream or huge Idea, wouldn't be good for our team...LOL which another forum

But I will tell you that there were many times in my life that I did rely on Metal Detecting and other "treasure type hunting" to help pay for a need or want, as I do still obv. do TODAY!
Great topic!! Never mind the finds,I guarantee there is someone out there that could think of something brilliant for monetary gains galore--just with all the trash we dig!