I did some rough mental calculations ....
Me too. I looked at the Luxemburg-Zürich connection. They have available seats on three or four days in November at a fixed time (what are the chances that your executive will want to travel exactly then?).
At 390 Euros a seat. How many seats does a BeechJet have? Six? So even if they fill all those seats, they will collect something like 2300 Euros for the flight. Handling/airport costs for departure and destination will be in the order of 1000 Euros, airway charges 100, fuel 500. Leaves 800 Euros for capital cost, maintenance, crew, crew training, operations, dispatch, office rent, hangar, catering, pubilcity. administration, ...
This year the fifth company I worked for in the business aviation and trainng industry went bankrupt. I think I know all about financial failure that one can know... All five of "my" companies had far more solid business models than this one here.