If it's a commercial project devs will be paid because they're like employees. If it's a small team making the project they won't have fixed salary. There's going to be donations buttons & donations links so devs can receive money from ppl who appreciate their work.
Unless the open-source product is produced by a company that has a relatively steady cash flow and a fixed amount of employees, then getting a salary isn't guaranteed. In fact, it's the opposite!
Are there open-source products produced by companies that pay their devs? Of course! And you can also contribute in these products, but if you 're not in their payroll, you will not get a salary.
I am sure there is no difference at all from what I said, is there?
I won't let this thread live for too long, if I have the time and interest I will create another one some day, in order to actually write down a list of people who do this.
You could probably find a ton of users that repeat what others are saying, but if you look for it you are just going to drive yourself crazy. I've opened tons of threads and the 1st 10 replies usually have 3 duplicate answers with words slighly different.
I would just report them to their campaign manager and that manager will likely take a deeper look at a user.