Marvel movies has such a high baseline of viewers that a string of flukes can be remedied by one major success and course correct from that. They have more than a decade of entertaining movies that earned audience trust. Even if Quantumania underperforms (I don't think it is? Yet?) I don't think those who skipped this decide they skip GoTG too, they'll evaluate based on its trailers and marketing engine.
Will that be good in the long run? I don't know but that's not my problem.
Probably because people usually enjoy films and characters on their own merits rather than any kind of “building a huge climatic event” just for the sake of it. Shared universe can make better and more enjoyable world building, but pretending that everyone get hyped to connect dots (

) or the reveal of new comic book villain with little previous mainstream presence. People love GoTG because people liked their films and their characters on their own merits, not because “Ronan is a Thanos lackey”

or “another infinite stone”

.
Is fucking weird how all of you are so hyped about stuff like that when you were hypercritical of DC films because it’s merits as individual films.
This kind of shit is why comic fans started to hate Comicbook events.