I think still the real problem with how and why movie adaptations of some comic books are more popular’s that the source material in this case’s just not readily accessible. To make matters worse, most people (even the curious) don’t always have time for those. It’s like if you want to get into comics but you use up the money on more practical stuff like food and clothing that you won’t have time for those anyways.
Movie adaptations of things like Harry Potter aren’t always any better but there’s a higher chance of somebody having any familiarity with Harry Potter and even technically owning one book than you have with let’s say a Superman comic book. It’s much higher still with romance novels, that’s if romance novels are more accessible and sell more than comic books do. This is a painful matter of fact.
It may be possible to find comics by chance but this gets complicated by many other factors and circumstances that contribute to its inaccessibility.