In the future I want to expand to Europe. So I checked some of the cheapest airports to fly to in a major city. I saw that Le Bourget in Paris is the cheapest but has no demand.But it has a ground Network connection to Charles de Gaulle and Orly plus many othe French airports. It also has a long runway too so why not fly there.
I’m missing a question here 
The Question is:
If it is so favorable to fly to, why don’t the airlines fly there?
( I think it’s favorable since it has ground connection to both Charles de Gualle and Orly airport. )
ground transportation has a ORS rating of 0 (zero). the ground transportation would count as an additional leg, so your overall rating for the flight from your hub to de gaulle via whatever that airport was you mentioned would get a very low and uncompetitive rating => no pax
Oh, ok Thanks very much.