I'll explain the concept by example.
I have 24 total pieces of furniture in my apartment, including shelves, tables, chairs, and other large things that can be made with wood.
When I own a house and some land later down the road, I'll be able to create most of this furniture, I estimate about 21 out of the 24 pieces of furniture, out of the wood on my property. I'll gain valuable experience and tools for the future, and the results will be very rewarding. Few trees will be used. I will save thousands of dollars by using basic tools and doing the work in my spare time, while still holding a profitable career. My quality of living will increase.
What is "bad" in my opinion? Making 0% of what you use is bad. What if you lose your job? What if the economy tanks? You are entirely dependent upon society, so you WILL suffer unless you find someone who wants your labor.
During the Great Depression, almost everyone's quality of life was in direct correlation to their ability to create more of the things they needed.
One of my old friends had a father who was laid-off by IBM two years ago in Vermont. Nobody wanted his specialized labor. He ended up selling generic labor in the form of random odd jobs for a few hundred dollars here and there. He almost lost his house.
One of my old coworkers was laid off by my previous employer directly after her husband was laid off by IBM. Nobody wanted their labor. They lost their house.
During the Great Depression, my grandfather hardly even noticed the economic conditions. Nothing changed in his life. Why? Because his family produced almost EVERYTHING they needed to survive, only stopping at the store once in a while to buy fuel, sugar, and coffee. Meanwhile, once-rich stock brokers committed suicide.
This is not theory. This is reality. If you cannot create anything but your own specialized labor, then you are dependent upon society and vulnerable to utter misery given commonly-occurring circumstances such as recessions, layoffs, wars, and famine.
No one wants to be vulnerable to these circumstances, but everyone is.