If it was 1 mil per coin, people will be buying 0.0001 or something like that, and early investors will be selling 2 btc (combined, at any given moment). The price will surely go down.
This doesn't make any sense.
Lets say im an early invest with 100 btc. BTC reaches one million. I sell all of my btc. The price will crash because of the fact that people wont be able to buy at 1 mil.
1) You could say that at any $/BTC value.
2) Why would you sell it all at once and cause the price to crash?
You wouldn't just put in the equivalent of a market order to sell everything at any price the moment someone else makes a trade at 1 BTC=$1 million. You'd put in the equivalent of a limit order. "Sell as much as possible, up to 100 BTC, at $1 million/BTC or above." If people aren't able to buy at $1 million/BTC (*), then the price would stay below $1 million/BTC, but it wouldn't crash.
Again, what you're saying makes no sense. Let's say you're an early investor in gold and have 10 tonnes of gold. The price of gold goes up to $10 million/tonne. You sell all of your gold. The price will crash because of the fact that people won't be able to buy a 10 mil?
(*) There are 7 billion people in the world. If 100,000 of them each bought 1 mBTC for $1,000, then that 100 BTC gets sold at $1 million/BTC. The only question is how much people are going to value BTC in the future. And we can only really speculate on that.
One person wouldnt sell 100 btc, but a lot of early investors could start selling totaling 100 btc at that time.