in the long run terra forming is cheaper as at a certain point it stops costing money, unlike a space station
Im not talking about space stations but self-contained habitats kilometers in diameter.
They cost far less as a space station as there is less maintenance.
You can easily make a radiation and micrometeor impact shield around your hollowed out rock for instance, simply by coating it in a metre or two of mud.
Planets will always be more expensive, hard-sf writers did the math decades ago.
It is far more expensive to get resources from your planet than it is to get them from small rocks floating around in space, if you live in space yourself.
They exist in purer forms and are more easily extracted.
A planet also has nasty side-effects such as weather and can never be as easily evactuated when it eventually breaks down and becomes uninhabitable, as all things eventually do.
You can house a few billion people on a planet, a few trillion in the asteroid belt alone, figures on how many can live in the Kuiper belts and Oort clouds are staggering.
Planets never stop costing money for a spacefaring civilisation if they wish to remain spacefaring.
Apart from utilising handy physics tricks such as building a space elevator or bolas, you have a very expensive gravity well to deal with for every export and import.
Lastly, planets are unpredicable.
Not only are there inconvenient things like weather and a large ecology that is impossible to keep under tight control (mosquitos, diseases), there are also dowright nasty things such as earthquakes and volcanoes.
A nice hollowed out rock the size of New York, spun up to about .95 of Earth gravity compared to Mars?
I know where I would want to live.