Truly stupid arguments!
you do not know when the first intelligent beings first started the conquest of the galaxy. They could be starting just about now and will be here in 2 million year.
at 10% of the speed of light, how long would it take us to reach the next closest solar system?
We may be the first intelligent life form that will conquer the galaxy.
etc. etc.
Forty years.
The likelihood that we are the first intelligent life in the galaxy is astronomically small. So is the probability that no one has reached us over the course of the last few hundred thousand years. Unless... there are unknown factors which make life much less probable than the best conjectures.