Costs of ownership are often underestimated, particularly with regard to maintenance. It's one thing to own a car and have occasional preventative maintenance, and the rare mechanical breakdown requiring replacing drivetrain parts, etc. It's not uncommon in an aircraft to need to replace components which cost far more than auto repairs, and in many cases, far more than a car.

The first annual inspection is often a shock to a new owner. This is especially true if the inspector isn't one who rubber stamps the annual and who ignores mechanical or legal issues. It's often at that first annual when the sticker shock starts to come home.