1) likely they are many players who bought this stock when it was new and have since gone inactive and it is still in their port
2) not all players who are currently invested in this moviestock have been invested since IPO (or invested in the same direction since IPO). Personally, I have flipped the Avatars stocks a few times, making a few mill each time.
3) Avatar 2 is priced at $338 and Avatar cashed out at $430. That is almost 100 pts that it could possibly make. Some players like that.
4) Some players bought at IPO (likely the lowest price for the stock) and are holding until delist so they can brag about what a good deal they got it at. Some players like that.
5) Some players have enough money that they can afford to invest in those moviestocks and just hold them forever (I have 8.8 bill in cash... and I already am invested in the Avatar moviestocks)