For example, you can buy KLM Air france for less than $3B.
It is a profitable business that does $30B in sales and $1B in profit. (and has been profitable since for the past 4-5 years)
[PDF] https://www.airfranceklm.com/sites/default/files/2026-02/202...
First, become a billionaire. Then, start an airline.
This margin seems terrible.
That said, certain sectors like software (as in custom enterprise grade software dev) pull revenues that are much much higher sitting around 35%, but it's not that common.