Tiny houses could provide needed cheap housing and upgraded models might also appeal to people. Here is an example of a higher-end model:

David Latimer of New Frontier Design is creating tiny homes that are more luxurious and more expensive than most you’d find on the market today. His most recent model, the Escher, starts at $180,000 and is designed to fit a family of six full time. Latimer calls this “the future family home.”…
The Escher is unlike most tiny homes, nearing $200,000 and including high-end features. But Latimer said that doesn’t make this model any less of a tiny house.
“Minimalism means different things for different people,” Latimer said. “The bottom line is that downsizing is a tremendous life adjustment and sacrifice for anybody. This tiny house is still a minimalistic lifestyle. It’s still a tiny home.”…
“I believe micro-housing is going to be a substantial part of the future of residential housing,” Latimer said. “Millenials and Gen Z are going to live this way. I would bet my life on this. Micro housing will allow people to live out the American dream.”
I am not surprised there is a perceived market for more expensive tiny houses. At a basic level, perhaps this is just selling the same products to different parts of the market: some people want to pay less for a tiny house, others will pay more. Indeed, from what I can gather about who moves into or at least talks publicly about moving into tiny houses, it looks like there are some educated people with some resources who want tiny houses with upgrades.
More broadly, I am not sure how a more expensive house fits into “the tiny house movement.” Downsizing and having a cheaper home are often connected to anti-consumerist motives and behavior. Some people make the choice to acquire a tiny house in order to move away from having too many items or fixating on a large home or being so financially committed. Does a luxury tiny house try to have it both ways?
If this kind of tiny house – small but still nearly $200,000 – is going to become part of the American Dream, the definition of the American Dream may need to change. For decades now, the American Dream involves owning a single-family home, probably in the suburbs. The Escher could indeed technically fulfill this – provide a single-family home in the suburbs – but it is very different in substance. If anything motivates people to make this the embodiment of the American Dream, it may be financial realities rather than aspirations for a simpler, downsized American Dream. In other words, expensive housing markets and debt may push people toward more luxurious tiny homes rather than a true desire to ditch the big showy house for a high-status small house.