We live paycheck to paycheck and are very happy with this. Though I'm not american...
I work 80% and my wife 60%, we got a massive mortgage so that we did not have to put up a lot of money up front and instead invest it.
So we don't really save any money from our paycheck, we spend most of it leading a normal comfortable life and whatever is left we use for renovations.
That said, our portfolio's combine to roughly 6 years of net annual salaries.
The gains we realise on this (which are untaxed in my country) outweigh whatever we could save by working more because the tax rate on labor is so high (55% in the highest bracket, where I am).