What do you mean by this? Do you mean "a non-negligible fraction of my measure is in a simulation" in which case you're almost certainly right. Or do you mean "this particular instantiation of me is in a simulation" in which case I'm not sure what it means to assign a probability to the statement.

So you know which I must have meant, then. I do try to be almost certainly right. ;)

(Technically, we shouldn't really be thinking about probabilities here either because it's not important and may be meaningless decision theoretically, but I think LW is generally too irrational to have reached the level of sophistication such that many would pick that nit.)