The lessons of the crash were: absolutely no one went to jail, and every banker involved made nearly as much money during the worst years of the crash as during any other year.
Ultimately so did the taxpayer. Those bailout loans everyone likes to complain about were some of the best investments the federal government has ever made.
I doubt those loans had anywhere near the ROI of, say, the land grants for the transcontinental railroad, the Louisiana Purchase, or the Alaska Purchase.
Actually, the government did very well considering that the loans (especially the AIG loan) were short term and fully repaid. The government made $5.6 billion on $67.8 billion loaned, the Federal Reserve made a profit of $17.7 billion.
The Louisiana and Alaska purchases didn't turn a profit for years, and took a substantial amount of additional capital. AIG is back to relative stability and pays taxes.
So, what's the problem?