So when Bitcoin was about 7 weeks old what percentage of Bitcoin addresses contained a majority of the Bitcoins mined at that time?
I think matt608's comment is extremely invalid. I believe that the exchanges are considered one big wallet. I haven't done a whole lot of research on this so I may be wrong. I'm definitely going to look into this more though.
I would bet the big wallets are pool owners wallets. They are skimming doge's off of miners and miners are letting them get away with it. Doge pools are one gigantic backroom skimming operation. Due to the amount of doge's that a miner gets per day, it is easy for these crooked pool owners to steal some coins from every miner. Miners need to keep track of what they should get and what they do get.