The logics of useing planets as spaceships

I think Alex Collier said there were 2 planet sized space ships comeing into our solar system, then NASA says there's 2 more planets in the solar system. He said that the moon is an alien spaceship. Some say that planetx is a spaceship.

So here's the economics of converting a planet into a spaceship. When making a very large spaceship, a lot of material needs to be mined, and brought up to space. If they want the space ship to withstand just the normal radiation of space from penetraiting to where the equiptment is, they'll need at least one mile of rock armor. So why mine a planet, when you need such thick armor, you'll just be disassembaling a plant and reasembling it somewhere else. It's more economical to just construct underground bases in a plant, and to move it with the directional movement effect. The univers is probably fully of life, and these spaceships will be disguised as planets to the less advanced races. Space is full of rocks big and small moving very very fast, and radiation storms, as well as enemy aliens weapons. There's little resisance to movements in space, so there's no reason to not have very thick armor on the spaceship. Cars, boats, planes, arn't made super heavy/big because there's resistance, and stuff.

Have a happy harvest.