Have you looked at how apps on the app stores are monetized? The only ones with a lot of success that charge upfront are big existing names or rare exceptions. Everything else that has success tends to be free. You can't compete with that, because somebody will just clone your app and release a free version of it with ads.
Targeted affiliate marketing is far better than ads imo. Odds are that you’re catering to a subgroup with very specific needs (unless you’re trying to clone facebook). You can inform users about products that they might need, ideally in form of valuable content and just include links with your vendor identifier. No third party scripts whatsoever and ads the user might actually like and click.
Of course there are. They also pay next to nothing and you're likely limited in scope in networks. Even then you need to be able to figure out that the ad network is actually keeping their promises. Remember that we're not talking about operations where you an just hire someone to do that. We're talking about operations where essentially you would have to figure all of that out and often take personal responsibility that you did figure it out properly.
