I'm not sure that many early investor coins exist.

1 million are Satoshi's.
1.5 million are lost from the first miners.

I know that the top members of the Bitcoin rich would be just over a million coins (excluding Satoshi.)

So if Satoshi and all the Bitcoin rich were to dump, that would be 2 million coins, this would also be a grand redistribution of wealth and I would imagine the price would recover fast and rise to a all time high too.

We can only dream for such a dump, but it'll never ever happen. Ever.

I think a dump of 100,000 bitcoin on bitstamp would bring the price to $10. However whoever did that would be throwing away 80% of their wealth for no reason, the price would again recover very quickly.