As a rule I don't begrudge people for liking a certain genre any more than I would for having a favorite flavor of ice cream, or type of music! =)
I have sympathy for someone frustrated that the thing they create with love isn't doing as well as they'd like it too. But it's not cool to belittle creators of other genres, or audience members for different preferences. (not saying you are, just referring to your example of people you've seen)
Also on long winded epic content: that takes a huge level of investment for the audience, and will probably be produced at a snails pace as a weakly comic, so it's totally realistic and predictable that slow growth could be a huge problem compared to a lighthearted romance that's easy to get into right away, or a silly slice of life that's funny on every page! It would make more sense, if one cannot avoid comparing themselves to others, to see a similarly themed epic long form comic that appears to have worse art/writing doing significantly better, then perhaps investigate what that person is doing that's having them rise faster. (Is it luck? Are they farther along? Do they create work at a faster pace? Is this their third comic and so they had an existing audience to carry over? etc etc etc.)