되다 here means to come off, work, or get accepted, and the 는데 clause sets up an expectation the result then contradicts. That gives both directions in these lines: I applied on a whim and got in, apparently I got picked, it does not work and yet it does. The rhetorical version is the same shape with a doubtful ending, asking do you really think that is going to work when the networks have it sewn up.