Carebears complain daily about griefing. They suggest that their style of play is paramount to all others, and that they deserve to play the way they want without interference from other players. They want single-player gameplay in a massively multiplayer setting. They threaten to quit EVE if things do not change, if the game is not made kinder and gentler.
Yet, for all their complaints, their numbers in EVE Online do not diminish. I would argue they're mostly reacting to consequence, and not really analyzing why they continue to play EVE. Even those who complain the loudest and most frequently seem unwilling to walk away from the game. Even given the level of frustration and grief that is, supposedly, heaped upon them.
What is griefing?
Grief  [greef] verbI really detest the word griefing. I prefer not to delineate player interactions into categories. Positive and negative interactions are relative. What affects one person negatively, likely affected the other side of the interaction positively (or neutrally, at the very least.) All interaction is desirable. It is this open-ended, relative interaction that is a hallmark of EVE Online. Interaction between players is the biggest challenge of the game.
1. an unexpected interaction between two or more players that causes loss of experience, items, time or reputation to one or more of those players in an online gaming environment.
2. an interaction that causes a disturbance or annoyance to one or more players, in an online gaming environment, by one or more other players.
So, those carebears who seem to really detest the social interactions that can and do exist within EVE Online, why do they stay? That reason can't simply revolve around EVE's genre. There are other science fiction MMOs that would provide them the safe harbour they seek. Star Trek Online, Anarchy Online, or Star Wars: The Old Republic.
Those games have proven to be failures. Perhaps those safe environments, where player interaction has become so minimal (chatting, grouping, trading), so ultimately meaningless, that players are tiring of standard MMO design far more quickly than they did in the past. What was once new, unique, has become run-of-the-mill. MMO design has become single-player (masquerading as cooperative) game play in an instant messaging wrapper.
Players don't use their wits when playing current MMOs. NPC battles are easily dissectable recipes. Achievement is defined by a never-ending cycle of collecting the newest and bestest stuff. There is no way to lose stuff, so the achievement of gaining it becomes hollow. There's no consequence. You can do the dumbest things and there's no penalty for doing so. The divide between the skilled player and the unskilled is ever narrowing. It becomes harder and harder to distinguish yourself in current MMO design.
If there's one thing players crave, it's to distinguish themselves from the mob. It might not be something we're successful at, but it's certainly something we all desire. If MMO design makes distinguishing oneself increasingly unlikely or difficult, then what's the point of playing massively multiplayer? One sheep, among many, grazing.
That is where EVE Online differs. And even those that claim they want to graze peacefully -- and they know exactly the games where they could graze without being disturbed -- stick it out in EVE's woods amongst wolves.
As much as carebears complain about certain types of player interactions (those that generally result in the loss of their ship), they also realize (perhaps subconsciously) that they need those interactions. They can't go back to the stale formula of rinse-and-repeat raiding and questing. There's a certain high they get while manning their Mackinaw in a mining belt, when suddenly Pirates of the Care-a-Bear'n jump into system. There's real and genuine consequence. They stack their wits against the wits of other players, not their wits against some easily manipulated and dumb AI.
After all the complaining, these carebears that stamp and stomp about "griefing" still stick around. It's not simply because EVE is sci-fi, and unique among sci-fi offerings. It's because EVE offers a level of challenge that no other MMO offers, it's because EVE provides a level of challenge that no MMO developer, except CCP, has had the balls to implement, even as those safe MMO environments are failing more rapidly than ever before.
Once the plunge into EVE Online had been taken, once the real nature of challenge and risk versus reward has been experienced, it is hard for these players, complain as they still do, to find fulfillment in a safe, risk-free gaming environment. Maybe carebears simply need to admit to themselves that what they rail against the most is what actually keeps them playing EVE.
The carebears doth protest too much, methinks.
 This is not an official definition of grief, as it pertains to gaming. You'll find it in no dictionary. But I think it's a good general definition of what defines griefing in a multiplayer gaming context.