I don't think you have an appreciation for how much fuel is required to adjust an asteroid's orbit to approach earth. Much less align with earth's orbit. Much l

I don't think you have an appreciation for how much fuel is required to adjust an asteroid's orbit to approach earth. Much less align with earth's orbit. Much less get it into stable orbit around earth. Or the fuel required to get the fuel you need to the asteroid. Fuel that has to be lifted into orbit. Which requires fuel. Go look up the costs of lifting equipment just into orbit. Then look at how much lithium is worth per kg. Then go look at the fact that we have exactly zero manufacturing capacity in space. Simple operations and repairs using pre-made parts on the ISS take hours-long spacewalks that require weeks of planning. And you think we can "build engines" on asteroids?