As one of my professors used to say, there are two basic types of psychologists - lumpers and splitters. The lumpers try to find the universal principles that apply to all people. The splitters like to focus on differences between people. My guess is that a balance of both approaches is the best way to go.
And that applies to cyberspace as well. I think there are some universal principles that are valid (like the effect of cyberspace anonymity as a disinhibiting factor). But like Doug says, there also are many individual differences in how people behave in cyberspace.