Source: http://www.americablog.com/2011/01/us-income-distribution-20...
Source: http://www.americablog.com/2011/01/us-income-distribution-20...
The income distribution tables from the last US census can be found at http://www.census.gov/hhes/www/cpstables/032010/perinc/new11...
Where else can you convince people to pay you well into six figures to sit at home in your boxers and solve puzzles?
Of those industries, how many of them not only allow, but encourage you to work short contracts at your whim, allowing as much free time in between as you'd like to spend that massive overpayment.
A good developer can produce so much value in such a short time that companies can afford to pay you pretty much any number you can say with a straight face. And if they balk, the bad/cheap developer they hire in your place will teach them such a lesson that when they finally come back you can double your figure again and they'll probably take it.
I tell ya, I used to bag groceries for a living. It was nowhere as good as this.