Without trying to uncover the grand scheme behind it, people involved in the travel business have options to book flights, hotels and packages for extremely low prices. I've seen offers for as low as 15% of retail value. He could very well be doing such a thing here. Reselling those offers.
Another option is that as for example star alliance has a corporate FFP where companies fill in their ticket numbers of their employee's after which they can book new flights. If one would have a company where lots of flights have been made but not much more, this would be a good way to get them paid out.
If I were a travel company I'd have an account on all those services and put all the sales in one of those