In the past twenty or so years, what has our attitude been?
What is the evidence that there has been only one attitude?
You've correctly identified the proximate cause of the economic collapse, but I don't think you've hit the mark on the attitude.
There's been a growing income disparity for a very long time in this country, and that has caused the general population to rely more and more heavily on credit leverage -- for tuition, with credit cards, and with mortgages. It's not euphoric greed and excess that's brought this about, it's been the stagnation of middle class income compared with the cost of living.
At the same time, this has been facilitated by the easy availability of credit. Why? Because the wealthy investors (not so much individuals, but rather corporations, investment firms, foreign treasuries), have gobbled up high interest securities (like credit cards and like mortgages) because the rate of return has been so high.
So the standards for credit have plummetted because investors have known that even a 5-10% default rate on mortgages is acceptable when 1) the interest payments are 9%, and 2) the price of housing has been going up and up and up, so that even defaults aren't necessarily a loss. This has motivated
them to make easy credit available.
I think there are indeed parallels not just with the 1920s, but also with every other bubble / collapse. I don't think there are with Rome -- Rome was just too topheavy, too corrupt, and suffered from invasions and plagues and decay. It was a much more chronic problem.