Large sell orders

There seems to be a lot of people on here with very positive outlooks ahead but why are there some serious sell orders in play at the current price levels?
Someone has a 800,000 share parcel for sale at $0.20 ($160,000) and there are some big ones at current 18c (500,00 shares for $90,000).
Surely if you have that many shares you are close to the fire and must hear the chat and have some solid insights into the future.
Does this make anyone else nervous?