There's little arguing that the wealth gap between the top 10% and bottom 10% (or even bottom 80-90% for that matter) has widened over the years. Look at the stock market booms in the mid/late 90's, around 2006-2007, and the one over the last 1-2 years--if you had your money in the market odds are you made some good cash, especially if you bought low. But little is stopping even the young Airman from living below his means, saving money/putting some away in the market, taking advantage of opportunities (free school, etc), and then bettering himself in the long-run. Will he ever be in the top 1%?...doubtful. Will be in the top 20%, definitely a possibility if he plays his cards right. Same can be said with the poorest of Americans even if they don't join the military. If they live below their means, take advantage of the opportunities (scholarships, government aid and grants, etc) and is always trying to live below their means and doesn't get himself in trouble (substance abuse, run-ins with the law, knocks a chick up) then he can definitely better himself as well. Sure, he'll have to work harder for it than someone born to a family where both parents make $100K+, but the fact is that the guy who started off poor can definitely improve his life. Hell, today the government gives out quite a bit of welfare (subsidized, and for the very poor, free healthcare), so they have that going for them as well, though I think that keeps in the lower class.
Check out the table: It shows how the wealthy is increasing their wealth at a greater pace after the last 2 recessions..but it is also showing that there is growth outside of the 'top 1%' (skip to the very end if you're not seeing my point). No doubt the last few years have been tough, especially for the folks at the bottom, but unfortunately that's what happens with a weak recovery.
Also, we have spent TRILLIONS of dollars on the 'War on Poverty' only for the poverty level to be documented as mostly un-changed. That being said, those 'living' in poverty are much better off than they were 40 years ago. Here's an interesting chart done by PA's Dept of Welfare which shows that in some cases, there is definitely a reduced incentive to better yourself.
And with the top wage earners in the US paying the most taxes, the country would be worse off if that wealth was truly 'spread around' with our current tax system. The Dems and the GOP are all about the corporate welfare--funny, under President Obama the richer are getting richer than they were before and the income gap is ever increasing...though like I said, the bottom half of the people still live better today than they did 40 years ago. I think the late Margaret Thatcher explains liberalism and socialism pretty well and better than I ever could: