I believe that I can't know anything with certainty except that I'm conscious and that I exist. I can't prove that anything exists outside my mind. I can't really know whether or not I'm living in a solypsism. I don't live like I'm in a solypsism only because I might not be and there may really be others.
Anything is possible. Perhaps Kurzweil's singularity has already occurred centuries ago and I'm existing in a virtual world where nothing is what it seems but just a projection of my mind.
Sometimes I wish I was the only consciousness because that would mean the world with all the pain and suffering doesn't exist and the worst that anyone has ever suffered would be what I went through.
Again, although I think that's a possibility, I don't behave that way because maybe it's not.