None of the above is necessarily correct. Many private owners do their own maintenance, and practise for emergencies. If you aren't renting you can take the time to train, the insurance and hangarage are paid, so it's just the petrol. And if the weather goes sour nobody is yelling at you to get the aircraft back.
Very true, PC. I was just referring to a type of owner that exists also, unfortunately.
It won't be just the petrol, there's the wear and maintenance on timed components, oil changes, etc. Otherwise you are perfectly right.