This might be true for you. I have lived with free wood for heating and it was more expensive for me than using a heat pump. What is expensive depends on a lot of factors, political, social, location, time and knowledge. It is not a clear dollar per delta T.

Chopping up a tree is kind of fun, we bill that to the entertainment budget instead of the heating budget. And it usually happens during a hotter season, so I might have to go inside to take a break, get a cool drink. So, we can bill some of the tree chopping activity to the cooling budget!