I think most of the answers are posted above. Change scares many people. A lack of what they know as security (having a stick and brick house) seems "crazy". Many of the people I have told about my wife and I's plan to go FT once we retire in 7.5 years act the same way. Blank stares, confusion on why someone they thought was semi-intelligent could be talking so crazy. Frankly, it's ignorance. They know nothing about the lifestyle, don't understand the liberation of shedding most of life's accumulations and living a simpler, freeing lifestyle.
I was watching one of the "living in Alaska" shows on NatGeo the other night where the person lives in a place off the grid. No running water or power, other than what he can generate with solar and a genny, miles by snowmobile in the winter and by boat when the water is frozen to the nearest general store. He was telling the cameraman, it thinks we are all crazy living the hustle and bustle lifestyle we do in the cities, having to slave for the $$$ to pay for things we consume and want when he can live free, do as he wants and hunt and farm the food he needs and live off the land. I think I agree with him but FT RV-ing is a lot closer to what I can manage at retirement, rather than building my cabin by cutting trees from my 40 acre property in Alaska. Maybe if I was in my 20's again ;-)