As others have said here, I have fantasized about it, but numerous things make that really impractical:
Firstly, I'm a data hoarder. My life unironically revolves around technology, computers, and digital downloading. Comics, movies, games, etc. I couldn't leave that behind because it's become more than a hobby to me.
Second, I recall a local story(I think it was local)where a man wasn't off the grid, per se, but owned his own private land, his own house, and had solar panels on his house so he didn't pay the electric company for electricity. He basically had one thing and one thing only to pay out besides gas and food, and that was taxes. Well the story goes the local government of the state actually forced him off his own land for no conceived reason, but they were somehow able to, and the likely reason was that they didn't want him just living free and happy.
Just like you can't ever truly escape your society, your society in turn kind of wants to keep you around, often times for money. Now yes you COULD go out into the wilds far away from society and do everything iron man style, no tech, build your own house, supply whatever you need for it, use candles or non-electric means of lighting, build a fireplace for warmth and comfort, hunt game, all that kind of stuff.
But I personally feel that as society continues to grow more and more land will get taken up by society. In the neighborhood I grew up in we had a small forest in part of it, and as I got older more and more of it got taken down to make room for building more houses. The same could likely happen to places that aren't protected under some law from being torn down, and overall I do see new buildings get made or buildings get torn down and rebuilt from time to time.
I imagine if one doesn't go significantly far enough away from society, they won't ever truly be free from it, and even then society could eventually catch up. Beyond that, there is no true way to live off the grid, though you could get close enough to it if you lived in a house located a five minute drive away from the nearest city, in a pretty empty and untouched area.
Third, Bringing in the iron man phrase again I mentioned, you'd have to be pretty capable to even do that. You mentioned helping with roofing of a bugout shelter. That's one of many things you'd be doing on your own or with minimal help if you tried that. As fantastical as it sounds, even the act of building a log cabin by hand is a grueling task. Personally, I don't ever see myself being fit and capable enough to do that kind of stuff, but that's just me.
I personally think some of the fantasizing comes as a result of media. Movies, TV shows, video games.
As an aside, I have been downloading ebooks lately that talk about a lot of things related to living off the grid or similar concepts, but mostly because they talk about preserving/salting foods, sharpening blades, wind and solar power, stuff like that.
Ideally, one day, I'd like to be the guy in the story I mentioned above, but without any government intervention interrupting my life and likely with me paying for internet and Netflix/whatever similar service is appealing. But even discussing solar/wind power is a whole other topic on its own, I know jack shit still about wind power, and afaik solar power takes a lot of money at the start to really jumpstart into supplying your whole house.