The point I think he's trying to make is that our economic system, to a greater degree than many of us want to recognize, hands out rewards arbitrarily. Merit alone will not get you there: luck and family connections (which is basically another form of luck) help a great deal more.
I think a reason we find this so disagreeable to think about is that it removes much of the incentive to work hard. If you are not wealthy and you don't work hard, you have a basically 0% chance of achieving wealth. If you do work hard, you have a 5% chance (for example). So, sure, if you want fiscal security then you have to work very hard, but even with hard work success is unlikely, with the factors other than "work hard" largely out of your control.
Then, of course, if you do achieve success it's easy to attribute it solely to your hard work (after all, again, if you hadn't done that, you wouldn't have been successful) - which is supremely annoying to everyone else as it very obviously isn't the case.
