To quote the adage, I'm a solipsist, and am surprised everyone else isn't too. I think any intelligent agent should conclude that it is probably something akin to a Boltzmann brain. You could plausibly argue that I am cheating with pronoun references (other people might agree with the solipsistic logic, but centered around them). Is that what you are asking?

EDIT

Is there anything about the world that you expect would appear different to you because of this belief?

Not really. I think some of the problems with AIXI may be AIXI acting rationally where the desired behavior is irrational, but that's the only time I can think of it coming up outside of a philosophy discussion.

Of all possible minds thinking the thought that I am thinking right now, most aren't living on earth, posting to Less Wrong. Most are random fluctuations in high-entropy soup after the heat-death of the universe, or bizarre minds capable of belief but not thought, or other deluded or confused agents. In all but a negligible fraction of these, you, maia, do not exist.

I could put numbers to it, but it would really be pulling them out of my butt -- how certain are you that anthropic reasoning is valid? If it is valid (which seems more likely than not), then you quickly run into the problem of Boltzmann brains. Some people try to exorcise Boltzmann brains from their anthropic viewpoint, but I have no problem with biting the bullet that most brains are Boltzmann brains. The practical implications of that belief, assuming the world is as it appears to be, are (I believe) minimal.