The $1400 was after he paid for eating/shelter. He's paying his parents $280 for rent - something he could do similarly by hooking up with some roommates. It's not glorious, yet he has the ability within his grasp to have an economic state of life that I suspect north of 90% of 40 year olds would trade their lives for. For a man who moves boxes for a living!
Here [1] is a calculator for investment fund returns. They're quite insane. Pick the absolute worst period for returns bust to bust 2000 to 2010 and you're still looking at a positive return. 1990 to present and you're looking at 10%. 2000 to present, going through both busts, is 6%. 2010 to present is 14%. 8% is not unreasonable - let's say it accounts for him possibly getting a raise sometime in the next 22 years.