And how did these toxic assets come to exist?
One version... Disregarding whether or not banks printed 0's to buy house from original seller via subprime buyer, subs then pay in pile of equity fees etc, cant pay, get foreclosed, bank outbids hopeful individual local homeowners and pays itself via court to buy from foreclosure auction, bank flips to market at retail or to 1%'ers in REO deals, everyone involved donates to Democrats campaigns who created the Socialist sub loan programs a cut of the profits. Many places passed law regs post 2008 surge to bundle the [tax] lots thus locking out hopefuls from ever getting a single. CDO's, bundling, remarketing, etc are another set of scams upon different entities, bond buyers, etc. Meanwhile China buyers, country CB's, other banks keep pumping prices and financing rental buildout instead of freehold. Welcome to slavery. There are youtubes wikis and boards on the schemes, before they censor and purge those too.