Nomadic Scope - How Many People Can Go Mobile?

I should point out that I am mobile only part of the time.  Most of the time I live in a house where I pay rent. My advocacy for going mobile is mostly based on theoretical musings and much less so by actual practice.
The truth is that nomads were always a fringe group and will probably continue to be so.  The reason is that nomadism is an adaptation to marginal environments where you have to move on a regular basis to find food.  In places where food is plentiful, you can just stay put.

In the modern city, you don't even have to leave home to find food.  Someone brings it to you.  What makes this possible is the miracle of petroleum powered transport.
But even before there was petroleum, people didn't roam around to collect food that was coming into season.  They stayed on farms and planted stuff.

While this sort of living was hard, it produced more food than nomadic lifestyles could.  Farming also meant that sedentary farmers controlled the land and kept nomadic travelers off it.  Farming also produced surplus food, making cities and population explosions possible.
So if everyone went nomadic, especially the farmers, there wouldn't be enough food to keep the whole population alive.  Not likely to be a popular idea.