The whole comparison thing started as posters here think Shazam did "badly", to show it didn't, we need to compare with movies with similar release dates or comparable budgets. I look at movies from various genres as limiting myself to just comic book movies (because cbm market exploded in past 7 years) will give a wrong impression that Shazam performed badly, which is not the case here, though I admit it could have done better, so it unperformed a bit.
In my last post, I did mention how Captain Marvel released a month before got huge success, as it was considered as "must see" movie before watching Avengers Endgame, I also mentioned how Avengers Endgame affected Shazam's performance as most moviegoers gave priority to Endgame, so there's no use comparing those two MCU movies to Shazam (even though both MCU movies were released within same two month period) as we all know they performed exceedingly well.
Perhaps a comparison could be made to Ant-Man, but again Ant-Man had less competition and had better star cast and a successful brand "Marvel" behind it. Shazam was deemed as "Kiddy movie / parody movie" and not really seen as a "Superhero" movie by some which also contributed to it's lack luster performance, which was not the case with Ant-Man. I think Shazam should be evaluated as a regular movie first rather than as a "Superhero movie". (it didn't even have the DC Intro)
Disney remakes of animated movies are supposed be successful, but we have seen that not all such remakes are successful (Dumbo) Similarly, a movie wouldn't be successful just because it's a comic book movie, we know some cbm's are not making that much money (Fantastic Four, Hellboy.)
Which is why it's better to compare them as movies first, as at the end of the day. Studios will use the usual accounting practices to evaluate the movie's performance, whether it was able to earn back it's budget or not. How that movie compares to other movies in same genre will be secondary concern. Also, while comparing the movie with other movies from same genre, various other factors need to be taken into account, factors such as month of release, competition it faced, marketing budget, critical reception etc.
For example, Spider-Man : Into The Spider-verse earned $ 375 M on a $90 M budget, that's great if we consider it's performance as a regular movie, but if we compare it with other animated movies, like Big Hero 6 ($657 M) we might think differently, still as a movie it did well.
I compared Shazam's performance to movies like Dumbo, Hellboy as they were released around the same time and had to face same competition. In other case, the movies like Rampage, Tomb Raider, had comparable budget / release dates.
Also, if we need to compare with other similar movies, take a look at Power Rangers (Worldwide Gross : $142 M) and it had a budget of $100 M, Fantastic Four Worldwide Gross : ($168 M) with a budget of $120 M.
Which shows that Shazam did OK business.