I don't understand who could possibly have this many BTC.
That is DeepBit's payout address. Whenever DeepBit pays its miners, it sends one transaction per miner, and each transaction comes from 1VayNert and sends change back to 1VayNert. The change from these thousands of small transactions adds up to create huge "total BTC received" amounts. 1VayNert has never actually contained anywhere near 10 million BTC -- that's just how much BTC it has sent to itself in change from transactions.
Here's a chart showing the balance at that address over time. It once nearly reached 12,000 BTC.
According to this forum topic it belongs to DeepBit (currently the largest mining pool)