Its an interesting argument hugh3, that the learning is insufficient payoff for 6 years of your life, but the cynic in my says the same could be said of going to college and coming out with a masters degree is Celtic Literature of the medieval period. (6 years, little employment in the field, not a Phd so you probably can't get a teaching job, etc etc).
Lets say he does make it into the PGA, and plays for four years and doesn't win a single tournament but finishes in the money in all of them. (note that generally the top 70 or so players all get some money [1]) Depending on his walk through that distribution he has a good shot at making a million dollars over four years ($250K/yr). Which would be the equivalent of having made 100K/yr for 10yrs.
The payment schedule is another area where the PGA differs greatly from other sports which appear to have a much shallower 'money' pool. (I'm familiar with Golf, less so with say Nascar racing or Tennis for example).
The other assumption in your response is this one "but... hey, I learned that I'm actually not all that good at golf." which is at the heart of the whole Expertise/Outliers debate.
The hypothesis is that there is a 'base level' of expertise which anyone can achieve with 10,000 hrs of focused practice. And once you have invested that time the difference between your performance and that of someone who was 'gifted from birth' will normalize out, or more precisely winning or losing becomes more statistical rather than expertise related.
No doubt he's getting some sponsorship money from Nike and others who are betting that he will generate enough publicity like this to put their brand in front of others who are attracted by his story, so earning potential isn't exactly 'wasted' so much as 'different.' It wasn't clear from the original article to me what sort of pay scale he might expect 'working for the man' as it were. So its hard to evaluate the opportunity cost of that path.
So if the hypothesis is correct, and he's rigorous in his training/practice, then he will make back much more than his 'earning potential' over those 6 years. Much like an investor listening to a start-up pitch which will take 6 years to disrupt the market. Give the guy credit for going 'all in'.
[1] http://frankosport.us/golf/Purse/index.html