There must be as many reasons for doing so as there are those who "Full Time".
Some by choice some by circumstances... (welfare system ?)
My only minor gripe is not with those such as you met..
But the So and Sos who do it to avoid tax Car Tax Insurance etc and also rip people off or worse.
I deliberately have not used the word travelers as that encompasses a multitude of life-styles and legality issues.
As has been posted many times there are many travelers woh are "Good Eggs" and simply choose that life-style.
It is possible to argue that as we holiday abroad in the winter and live in the MoHo in the summer that we are travelers..
Yes but we pay tax etc etc