That doesn't answer the question of why there would be thousand of people on Mars willing to pay exorbitant prices for stuff. What is the "gold" in this analogy?

Its a planet with similar composition to ours. I am pretty sure that there is plenty of gold.

I guess if you could produce materials on mars it would be much easier to build and deploy gigant structures into space (lower gravity and escape velocity)

Mining is something that is always mentioned in scifi, but I am not sure how profitable it would be, I guess if propellant can be mined on mars it would be pretty doable.

Performing activities that would be environmental risks on earth would be relatively low risk on mars, due to the fact that it is already a wasteland.

Tourism would be a thing as well which would require many trades of comfort

The gold is scientific discovery & progress. If you don't think there is a crush of scientists, geologists & the like chomping at the bit to do in-person science on another planet you're a bit nuts. Add to that the glut of people who want to go for sheer adventure. All of those people are going to need "stuff" when they get there.

What would a "new market" on Mars really look like? Living on Mars would be extremely harsh for the foreseeable future, inhabitants would be struggling just to meet their basic needs for many, many, generations and the life of a successful Martian entrepreneur (in terms of material wealth) would be comparable to an American pauper.

In a way, it would be a very luxurious lifestyle; all basic necessities would be taken care of by automated systems. It's not like you'll be slaving naked in the fields to cultivate the crops. Probably it would be more like sitting at a workstation all day, monitoring life support systems and sending orders to the robots.

The hard part would be missing the fresh air, green fields and blue skies of home. But, if there's an eco-catastrophe on Earth, there may be nothing to go home to.