Anyways, most of the hackers do it just because they can... to prove that the system can be penetrated... curiosity...
Shorting millions of ether is not that easy to do over few hours and would mean he is the attacker. Unlikely as this could also expose him.
A $3M Ethereum short occurred on Bitfinex just moments before the attack; some claim this short closed with almost $1M USD of profit.
She did not have to do it over few hours. This exploit takes a long time in making.. you have to propose a split and wait for the voting period to expire..then you recursively call the split function after theDAO sends you money but before it updates your balance.. (I was able to code the exploit yesterday, pretty basic..let me know if anyone wants).. Hence this attack could have been more than a month in making..and atleast a week..
Sure you can put on pastebin and share the link. Would like to look at the code.