The douchebag is someone — overwhelmingly white, rich, heterosexual males — who insist upon, nay, demand their white male privilege in every possible set and setting.
The douchebag is always a white guy. But he is more than that. The douchebag is the demanding 1%, and the far more numerically significant class of white, heterosexist men who ape and aspire to be them. Wall Street guys are douchebags to be sure, but so is anyone looking to cash in on his white male privilege.
This narrowness of categorization — perhaps unique in the history of America’s rich history of racial and sexual slurs — is what makes the word douchebag such a potentially useful political tool.