Why don’t you bake your own bread OP? It’s much cheaper and without additives.
Why spend £20 on a dress, OP when you can buy the cloth for a fiver and sew it yourself?
While you’re at it why not weave your own cloth like a good roman matron? If you grow and pick the cotton it will only cost you 20p for the seeds.
Why not wash all your clothes by hand? A washing machine is over £100 and hand washing is free.
Why not live in a tent, OP. An actual house is several hundred pounds a month and a tent is £100 one off. You can gather firewood to keep warm in winter.
In fact why go supermarket shopping when you can grow your own food. Buy a fertilised chicken egg and in a few short weeks you can have a chicken dinner for the cost of an egg!
To answer your original question, the answer is time.
We use money all the time to pay others to do specialised tasks which we could do ourselves, but they are faster and more efficient and effective.
I can come home from a long day at work/looking after children and clean the bathroom and toilet or I can pay someone £10 to do it. With the 30 minutes I’ve saved I can read a book, watch an episode of whatever. I’m now not too tired to make love and I’m not grumpy and snapping at my children.
I don’t smoke, I don’t have a shoe habit. I just use the money I would spend on that on a cleaner.