Paul Krugman joined in ridiculing billionaire Jeff Greene, a person who richly deserves to be ridiculed. (He wants people to get used to lower living standards.) However people are wrongly attacking Greene when they complain about his betting against subprime mortgage backed securities.

Subprime mortgage backed securities were the fuel for the housing bubble that entrapped tens of millions of people, laid the basis for the economic collapse, and ruined millions of lives. The securities were in fact bad. Greene betting against them made that clear in the markets somewhat sooner than would have otherwise been the case, bringing down the bubble earlier and more rapidly.

This is good. It meant that fewer people were caught up in it than if the bubble had continued to grow for another six months or year. It would have saved people an enormous amount of pain if there had been lots of Jeff Greenes betting against subprime mortgage backed securities in 2003-2004. They could have prevented the housing bubble from ever growing to such dangerous proportions. Certainly his actions were much more commendable in this one that the profiteers and enablers like Robert Rubin, Alan Greenspan, and Timothy Geithner. 

Just to be clear, Greene was acting out of greed, not a desire to help the economy and society. But this is a case where greed was good. Of course he is still a wretched person, flying across the Atlantic in his private jet with two nannies to tell the rest of us that we will have to get used to a lower standard of living.  

Note: Name corrected -- thanks John Wright.