The reasons for building a tiny house

The reasons for building a tiny house are many and the first to come to mind is money, or the lack of it.
Small houses can be built for a couple of grand if you are prepared to do the work your self.
The foundations seem to be the expensive bit but this doesn't have to be so. You are already outside the box by wanting to build small so why not continue with this thought. In the 1800s the people built themselves or lived in the open. Wooden piers were the starting point, as that was all they had was wood set straight into the ground but the surfaces below the ground were chard over an open fire. Today steel is plentiful and relatively cheap if it is sourced secondhand.
I have seen where in this modern day a Jehovah Witness hall was built on steel angle iron on steel piers above the ground and then the walls were bricked up on these angle iron. There was no trenches and the proverbial mountain of concrete in the footings as in regular build.
Set in concrete steel piers are a good starting point. I am a steel worker and steel is only natural to me.
The sizes of steel required is way less than timber because of its higher strength. My Gypsy wagon is made from 20x20x2.5 square steel.