Bearing in mind that freedom means no restrictions. You supporting your family doesn't sound particularly free to me. I don't know what you did with the 'freest time of your life' but you presumably had to either earn well or restrict your spending to do the above. You may not have had children, but you certainly seem to have had erm responsibilities.
What I find odd is that you equate 'not staying at home' to freedom. If you explicitly want a world traveller, frequent mover, that's fine. But to say that someone staying at home 'restricts themselves' makes no sense. Someone could live away from home but stay in the same town and work the same job all their lives.
What PP was saying is that if you have the choice between renting and staying at home. In the same place. The latter makes more financial sense. They are not saying that you should restrict yourself to living at home and never moving anywhere else. As @breadandroses1992 put it her DH was already from London, with a wealth of opportunity. If he was going to stay there anyway. Why should he pay rent? What benefit would it have brought him?
Also, those living at home can be free (if their parents are chill). Spending on whatever they like, travelling whenever they want. They could move out, if they want to so there's no restriction here really. DH parents had a big enough house for people to stay over, GF's, roll in at 2 a.m. no issue. He left to work elsewhere but if he'd stayed home he'd have lost nothing, but gained £££.
I'm sure there are some who want to live at home and base their life choices around it, a lot of them probably have SEN but IME those who live at home - they'd have rented in the same place anyway. People are not giving up, say London life for a rural backwater just to save.