Can anyone explain how bitcoin cash has any value, where did the money come from, from thin air ?

Think of the classic supply/price and demand/price curves. They intersect naturally at a single point, which is the equilibrium point of a free market.

Now think of space for transactions within a given unit of time as a good which has its own supply and demand curves.

Now think of the block size cap as a production quota that artificially reduces what would otherwise be the free market supply of space per transactions per unit time. This forms a vertical line on our graph, to the left of the equilibrium free-market intersection point of the supply/price and demand/price curves.

There is now a triangle formed by the supply/price and demand/price curves, and the line at the maxblocksize transaction cap. The area of this triangle is wasted capacity of the system. It reflects the waste inherent in artificially reducing the capacity of an economic system.

Bitcoin Cash (effectively) eliminates the production quota, allowing the supply/price and demand/price curves to meet at their free-market intersection point. This reduces the 'waste triangle' area to zero.

This unleashed value is where the additional dollars are coming from.

Of course, as in any spring/mass system experiencing a step function, there will be overshoots and undershoots as price discovery is carried out.

Hey - I found a picture. It is meant to illustrate price control rather than production quota, so in our case, the orange squggly is the applicable loss area: