Oh yeah, and don't forget about all that sweat equity that you do yourself, that has an opportunity cost compared to what you could earn with that time.
If you do the renos for love and "hobby" that cost is reduced, but it is still there.
If you are someone that wants to just "hang" in their spare time, and you have to pay someone to do all the "work" rarely will buying make sense.
Like the extra, it is the same thing. Having time, doesn't mean that the time will be well spent. People can game a full-time job of hours a week, but complain they don't have enough money to invest. If they spent half that time working at a fast-food joint, they would be far better off - but who wants to take a second job at a fast-food joint?
I think that a person has to consider their own willingness and likelihood of behavior, when looking at the op cost of time spent. It is the same thing with - if I had bought 1 dollar bitcoin I would be worth hundreds of millions now.... but how many would have held? Most would have happily sold at 3 dollars and feel pretty good - at the time.