Haha.. you are right.. it won't go to 1 million overnight.

Let me give a more realistic example:

If on the markets.. there are 10BTC worth of orders for a coin.

If someone came and tried to sell 10 or 20BTC on that market, the price would plummet instantly to 0.

There needs to be enough people ready to buy up all that bitcoin.. or otherwise the market crashes.