All community fish will eat fry if they can catch them. For live bearers, the fry tend to stay at the top of the tank, so fish that go to the top get those, like Danios, Angels, Gourami's, etc. Cichlid fry stay at the bottom of the tank, so they are fair game to most all the other fish.
African Dwarf frogs are really bad at catching fry. They have pretty bad eye sight so unless a fry swims by them, they wont see it. Unless mine happen to be hanging up top in a floating plant, or a guppy fry swims by one at the bottom, they never get a fry treat. When I feed the tank frozen blood worms, I have to dangle some right in front of my frogs or they wont get any.
As for trading or selling the fry when they get bigger, that is really hard to do. Most all stores will not take live bearer fry because they breed too easy and there is always an over abundance of them. If its a fish that the store does not get from a supplier as often as they like then you can set up a deal. I trade my Bolivian Ram fry to 2 lfs for credit when they are 2". These 2 stores will gladly take them, but say no to Guppies, Platy, etc. They are picky as to what African Mbuna too because they also spawn so easy. Almost all chain pet stores (Petsmart, Petco, etc) will tell you no because their policy is only working with their suppliers.
So, if you try to save all the fry, grow them out and then cannot sell or trade them, then what? You then end up with an overloaded tank and all the fish suffer.
Do I feel bad about it? Sure I do, who wouldn't. I have a floating plant in my community tank and it is there for fry who make it up there. Most of the time I have one make it past eating size. Again, the smartest, strongest. In my Mbuna tank I have lots of hide outs for fry. If I find one that has made it past a certain size, I keep it for myself or give to friends.
I may feel bad about it, but I would feel so much worse if I took away the favored mate of a fish and the one left dies of loneliness (I have seen it happen). If I took one of my Rams away, the other would die. They are together all the time.