Solipsism, as you know, is the belief that nothing actually exists except a single being, which conveniently and necessarily is the solipsist himself. Asolipsism, on the other hand, is a word I just made up that means the belief that solipsists do not exist, at least not outside freshmen dorms and other madhouses.
I am an asolipsist, more or less; I think solipsism, not just as a held belief but as an idea that needs to be taken seriously, is something everyone should outgrow by the age of nineteen. Certainly you don't run into many self-declared solipsists. (Ironically, solipsism doesn't even have to be false for every solipsist to be wrong.)
Still, there are various weaker forms of solipsism that -- though no more valid than the strict, "Mysterious Stranger" version -- do thrive today.
Perhaps the most common form is selfishness. Many people don't believe they are the only existent being, but do believe they are the only existent being that counts, that "what matters" ≡ "what matters to them." ("&equiv.;" is the "identically equals" symbol, which basically means you can freely substitute the one expression for the other in any statement without changing the meaning of the statement.)
Others have a way of projecting themselves in a way that makes them normative of everyone. In their minds, society ought to conform to them, not as the selfish would have it because they are personally so wonderful, but because their own tastes and opinions happen to be an objective improvement over everything else. Such people think others ought to be like them, even if they aren't.
I'm coming to see that habitual hasty generalizers are also solipsists of a sort. The hasty generalization is of course the logical fallacy of "generalizing about a population based upon a sample which is too small to be representative." Committing this fallacy habitually is a sort of solipsism because it acts upon a habitual belief that the sample of one's own experiences is representative of the whole.
In the wild, this often takes the form of thinking one can form a sound judgment on a complex matter based on one or two bits of knowledge (which aren't necessarily true).
Now, judgment almost always has to be reached without knowing everything that might affect it, but prudence dictates that the firmness with which any judgment reached be held is conditioned by both the need to reach judgment and the relative amount of information used to reach the judgment. In other words, how strenuously I defend my judgment should depend on how necessary it is that I reach a judgment and on how much evidence (of all possible evidence) I use to reach it.
The hastily generalizing solipsist will think -- or at least act as though -- the evidence he has is all the evidence required to reach a firm judgment; he may also think that it is important if not absolutely necessary that his judgment be declared. Both are exaltations of self.