mathematically the chances of planets just in our galaxy that have life is something hundred billion so yea, intelligent life isn't much of a stretch, it's obviously far rarer than just simple life like bacteria
we've also found proof of existing life elsewhere, just not life that is still alive
we also estimate earth to be a bad life sustaining planet, like we're pretty bad compared to the average planet with life lol..
why we aren't looking for a alternate planet is because to travel out of our solar system it would take many generations.. we would need a ship that has infinite fuel that it generates from probably solar & also momentum or something.. possibly even human energy powered, it would also need farms and produce oxygen within itself (obviously / hopefully the farms would do that) so the ship would need to be massive in size
what interests me are the ships trying to be designed like tachyons so their minimum speeds are slightly faster than the speed of light, it seems out there but everything we know and have in average life styles were impossible and didn't exist a couple hundred years ago, so who knows what we'll know 100 years from now