You also need to maintain those planes, employ staff across multiple countries and timezones, and comply with insane amounts of legislation for every country you fly into.
Are you seriously comparing that to ... serving food?
The biggest two issues when founding an airline are getting your hands on some money and finding a profitable set of routes. For what it's worth, it's possible to do this as a former formula1 racer (Niki Lauda / Lauda Air).
Or a one-plane vacation charter.
It becomes much more complicated as the number of bases and planes multiply.
And if you get sloppy or unlucky, one or two crashes is enough to end even national carriers like Malaysia Airlines, regardless of who is at fault.
There are clever airline founders who serially start multiple successful airlines, so there is some mgmt. talent involved.
Source: commercially-rated airplane pilot.