Who supports OpenVPN and how do they pay for their servers if it is free? I am interested in using it but feel I should know how they profit so that I know it is not a scam.
OpenVPN is a piece of software that you can install on your machine, not server you can connect to.
There are of course certain sites that offer free VPN services using OpenVPN and those could indeed do it to spy on you. There is absolutely no way for you to know.
So if you chose to use a VPN provider that you can not entirely trust, make sure that you do not open any unsecured but sensitive connections while connected to it. An example of that would be an unsecured email connection from which the password could easily be sniffed.