[tharkun__]

I wouldn't say irrelevant but definitely nuanced.

Putting more insulation in the attic does not mean redoing the roof. Depending on what you have it might just be blowing in some insulation or adding matting. Of course there are options like spray foaming but it's not the only one.

You are of course right that if your walls are completely uninsulated you will probably want to rip out that dry wall and that will cost you. Maybe blown insulation is an option too depending on your specifics.

Do some math and see if it makes sense to do it if you don't want to do it purely for the sake of the planet. Drywalling isn't that big of a deal actually. The worst would be the ceiling and you don't have to touch that. Regular drywall on a wall is easily done solo by a home owner. Been there, done that.

It's funny what money makes you do. I had a choice to pay tens of thousands to have professionals do it or pay hundreds for materials and do it myself. I did lots of TIL and I have beautiful white walls again.