The problem I have with your third option is that it does not best prepare humanity for future problems. Right now humanity is mostly fighting known opponents and problems and they are all reasonably solvable for us. However, what happens at some point in the future when we have to compete against a yet unforseen opponent? Simple sci-fi examples are aliens or robots. Perhaps more ‘realistic’ examples are asteroids colliding with the planet or a nearby star going supernova and ejecting some large chunk of matter at us.
If we do your 3rd option humanity as a whole will not be as advanced as in option 2. When the time comes that we have to deal with an as of yet unknown opponent in our quest for survival our chances of surviving will be higher with option 2 than with option 3. So in option 3 the chances of all of humanity being wiped out are higher than in option 2, which is why I have such a big problem with option 3 (and 1). I want humanity to have the highest chance of survival (as a species), regardless of the cost.