I certainly hope there will be a lot of (rich) people who'd find life on Mars appealing, but I'm extremely sceptical there will be many people like that.

Depends which parts of Sahara, some are certainly livable.

Mars is a lifeless desert and you'd be mostly stuck inside anyway to avoid radiation. But maybe the goal of building a self-sustaining colony would give the people a clear purpose that would offset the discomfort.