I use JSX for quick flights between San Diego and Las Vegas. 

Plane interior is very cheap, but you waste less time in sketchy airline terminals dealing with TSA “security theater” nonsense, baggage theft, etc.

For shorter trips, where time spent in terminals represents a larger share of your total travel time, JSX is indeed a game changer. 

I’m considering a subscription to SetJet though. I suspect they may provide a better in-flight experience than JSX.