There’s really not much more needed.

Just food and air.

The reason why Mars is a desert today is because life just never happened to have developed there, but if it had, it would be as inhabited as any fertile land is.

Fertile? Martian land is not fertile. It is incredibly barren. Even if you somehow solved the atmosphere problem, you couldn't grow things there.

Only earth has the soil needed to grow things. Eons of things dying and being processed by worms has transformed wide swaths of the planet into fertile soil filled with nutrients that plants can draw on. Martian land has none of that. It's just rock and dust. Even the Sahara is more hospitable.

Processing Martian soil to be even remotely "fertile" would be very energy intensive even if you brought it back to earth. "Terraforming" the soil on Mars at scale would require massive amounts of material from Earth. And then you have the problem that Martian gravity is too weak to retain a breathable atmosphere, even if you could magically conjure up a planet's worth of air.

Even if all of these problems could be solved, Mars has no oil since oil is also derived from life. What does it have beyond "sunlight, CO2, water?" Earth has all of that and so much more, in abundance.

I'm sorry but you simply don't understand geopolitics at all, nor the sheer scale of what you're imagining.