One other thing when considering buying vs hiring is something one of my friends used to bring up a lot when talking about his boat.
If you have your own, and especially if it's hangared at the airfield you have way more motivation to just go flying.
Whereas if you need to hire it, you not only have get the right weather, have free time, but you also need to make sure that the plane will be available and that's just another step that brings you to the too hard territory.
If you have an aircraft ready to go you can always pop in before or after work, or whenever you have some time, without any prior arrangements and fly for as long or as short as you need.
If you need to hire one, you need to know in advance, arrange the hire, specify how long you're going to fly, etc and then you just give up...