Yes, I agree but you see the difference between computer simulation of a single planet (you don't have to simulate the entire universe to simulate our civilization) and Norse Gods, right? You see how one is fairly reasonable extrapolation of our current capabilities and the other is fantasy? Of course we don't know if it's possible to create a conscious, intelligent being in a computer but we also don't know what actually makes as conscious and intelligent so we can't say it's definitely not possible. Similarly we don't know exactly how life on earth originated (complex life even less so) so we don't know how probable it it's it exists in other places. Simulation theory is definitely more similar to extraterrestrial life than Norse Gods. And when it comes to it's probability we simply don't know.