SMOUC - I'm sure others here that own a/c will come to the defense of the prices on offer at the moment, but i've also got a few friends that own a/c, i've seen some bills and trust me you'd pay the hire rates a lot easier if you saw it.
I agree they have gone through the roof in recent years but so has the price of fuel, and most of the airport owners have doubled if not tripled their parking fees. Take into consideration engine/prop overhauls, brakes, tyres, 100 hourlys, insurance, if IFR instrument inspections it just goes on and on.
Also when the things are worth (depending on models) up to $200k you can't begrudge someone trying to make a few bucks in the process(if they do) Most of the time any money they might make they normally put back into the a/c with a new paint job, avionics etc.
I personally thank any person that owns an a/c and put them online with organisations and allow others to fly it, at the end the day I feel in most cases the hirers get more out of it than the owners do especially the way some people treat them.