One quibble: it's not them, it's their parents.
There are 18 year old entrepreneurs who've created lots of economic growth, of course, but they're very much not the crowd we're talking about here.
History will not be kind to this point of view.
One of the caveats of capitalism is that capital creates capital, wealth accumulates naturally at the top. This is why it has to be balanced with strong social welfare systems to avoid reverting to feudalism.
I don't know much of NYC but isn't it... huge? I'm sure that there are parts of it far away from Manhattan that aren't shitholes and where you can live with a "normal" wage.
If you want to own property elsewhere (Brooklyn, Queens, SI, Bronx), you need to be upper middle class and have some savings—no millions needed though unless it's some super prime location.
The 1% that commute long hours to Manhattan do it because they want to live in their large Long Island or upstate estates/houses, not because they can't afford Manhattan. If they wanted to be close to work, they'd just have to live in a smaller house/condo without a large front lawn or private pool.
Millions of families live "decent" lifestyles in NYC all the time without being millionaires.
See here: http://streeteasy.com/condos/midtown-east?sort_by=price_asc
Cheapest studio condos go for upwards of $500k.