[rspeele]

Couldn't this simply be a wallet held by an exchange managing a large number of customer's DOGE holdings?

If this was a long-term storage wallet, it would make sense for it to have steady deposits and few withdrawals (in big chunks, going into other "hot" wallets held by the exchange, from which withdrawals to individual customer withdrawals are sent).

Assuming they're solvent, the exchange has to hold DOGE backing up all their customers balances. Since many customers never withdraw into their own wallets -- especially for a short-term trading coin like this -- that balance managed by the exchange will be substantial and grow during times of high trading.