Agreed. That's typically the 'rule of thumb' but it can vary from machine to machine. Charter operators will give you numbers that support chartering 100% of time, and aircraft brokers will give you the same numbers to support buying a machine yourself.For example, our Citation Bravo is actually closer to $1,200 per hour in Direct Operating Costs (fuel, engine programs, etc.). I've read that owning vs chartering starts to make sense around the 200/hr per year mark, although I've never done the math.
We fly private "semi regularly", however there are times where it just doesn't make economical sense, which we'll then go commercial. My Father flies private most always. You'd sooner meet God himself than find him standing in line waiting for a gate rape from the TSA. He'll go commercial over the pond.
There is nothing in the world that truly justifies the cost. However the quality of life is incomparable. It's truly an earned privilege.