Those things must make money or they wouldn't be adding more. It can't be from ticket sales though, some of those lower tier bowls have damned few people in attendance.
The main things to remember are bowl games are put on by the local business people and chambers of commerce to get visitors in the city to spend money. It is an advertisement for their vacation spots etc. And also the big corporate sponsors are paying for a lot of the expense of the bowl game as a corporate tax write off which they can afford since most of those big companies do not have to pay any US income tax.
And with TV money and other companies paying for the game through commercials we should not even worry about how much money these bowls lose or make or how much ESPN loses on the game.