Tree structures are awesome but there's a few considerations.

1. penetrating the tree to lago-bolt or nail into it is problematic for the tree. It opens it up to infection and it reduces the tree's mobility in high wind which is what is supposed to keep it from falling down on top of you.

2. Lashing (rope) techniques are favored for affixing your house to a tree and be sure to use NON STEEL BELTED RADIAL TIRES as cussions between your lumber and the tree. One of the most sensitive areas to a tree is the green layer just below the bark. That's your tree's circulatory and nervous system.

3. Know how many of your local building codes "permit" you to build a "residence" in a tree? Not too many. Keeping such structures termed as temporary play houses is a good way to think. This implies a reduced level of lifestyle expectation not spoken of in the pics that the reference links to.

4. Of course if you are a multi billionaire, screw it, you can build what you want wherever you want.

    The motivations are valid, but there are better options than trees.

     Unless you can sell what you own for some major "change", you'll be pretty hard-pressed to afford a "modern" and functional treehouse. It's bad enough that you will have to put up with high winds, forest fires, woodpeckers, ants, various varmits, and a position as a "sitting duck", but the idea of doing this (unless yoou are a highly proficient contractor) in the face of zoning and other "social" hinderances, makes such a project just a little more than an alternative living arrangement.

      For those who are truly concerned with the likelihood of social collapse and a need to "get out of Dodge", "off the grid", or "back to the land", before everything collapses, the answer isn't likely to be an adult playhouse in the trees.