no one else would bother to mine them then, you'd own all the rest of the bitcoins besides Satoshi's who disappears in 2010 and then you disappear in 2011 with your 5 million, no one remembers what bitcoin is and you'd have a net worth of 0! yay
People would always mine BTC as long as it's profitable enough to cover the electricity costs and some of the equipment costs, which is a pretty low margin. But having 5M early coins on top of Satoshi's coins concentrated in the hands of a single individual would be pretty toxic, everyone would be afraid of a huge crash when this individual would start selling and the addresses would be closely monitored. But if the coins aren't moved for a decade, people would start assuming those coins as lost.