How do progam owners make money off this? Is there a profit potential here, how do these do?

Well, I' m the owner of lotofhits.com,so I could answer this question.

Well,we usually sells traffic for webmasters or redirect the free credits to pay to promote sites and also sells specials membership,and banner and ads space.

My site is very little and really don't provide earnings(I pay the host and it's difficult to afront the pay outs(I own a paid traffic exchange)

I suposse that bigger traffic exchanges will do some money but it' s difficult too do a big bussiness,with it.We usually have a great traffic amount(from users that surfs hundredes of sites every day...) and theres not many interesting advertisers...
There are too much people on this business,and we usually don't have the advantage of PTR sites that uses oither programs to advertise...

A difficult market,but,none knows,perhaps some people gets benefits(if someone knows some secret to do it so,please contact me!!!!