Is one’s online personality different than one’s real life personality and which one is the true personality?

This question has come up from time to time here on WebDip, and last night, I had an experience that made me think about this again. So, I couldn’t sleep last night since I have insomnia once in a while, and I decided to play some Diablo 3. I had recently bought a pretty darn good piece of equipment and I was going to try to sell it for a reasonable profit. A player contacted me and asked what I would like for it, and I said 10 millions gold (slightly overpriced because I expected it to be bargained down to 5 to 6 millions). He said no thanks to the initial price, and I said “hey, give me an offer, you never know if it’ll be reasonable and I might take it.” Instead of giving me an offer, he told me that it was worth 200K and that if I can find anything on the Auction House (an in-game place where you can buy/sell to all the players by listing equipments as auctions) for more than a million, then he would pay me the full 10M. The cheapest amulet on the auction house that had three of the four important stats compared to the one I was trying to sell quickly was 3M, and I showed it to him. Then he said people are idiots and idiots would buy anything and that the gear was still worth only 200K because he knows the auction house. I then asked him to buy a comparable piece for that price and I would pay him at least that much. At this point, he started to call me a boy and told me that I was up past my bedtime. I then knew that this was problematic and I should just stop talking to him, but I felt the need to explain what a reasonable discourse was and that he had no reason or evidence to call me any such thing. His retort was that I must be a child because no grown man would take the time to reply to him and what he said. I blocked him and went to sleep.

So this got me to think about one’s online personality and one’s real life personality and which one is perhaps a more accurate reflection of a person’s “true” personality. In particular, I know that some people have said this forum allows them to vent, to say things that they normally wouldn’t say, and to take their ideologies to the extremes partly due to a lack of repercussions. To a certain extent, I do not disagree with this. However, I posit that if social conventions or repercussions are responsible for the differences between personalities, then they are merely curtailing the true personalities that lie beneath. In other words, the online personality is closer to how we actually are since we are allowed to be ourselves without the external constraints of social expectations or without the fear of being punished. Even as I write this, I know that it is not a case of just black and white but shades of gray. If someone is a belligerent know-it-all asshole online, then can he be that way in real life as well? Well, sure; no reason why not. Is it likely that someone who is considerate and thoughtful in real life would be a complete and utter horror display of a human being behind a screen and keyboard? In my opinion, not very likely but it is ambiguous. So, what psychological and/or social factors could induce such a shift in one’s personality from a commendable flesh and blood to a less than reputable digital?