You can generalize whatever you want, but there are some real reasons that the results of THIS poll are likely not representative of the general phone-buying public, here are 3:
1. Sample is not randomly selected. People self-select to participate based on the title of the thread, which is literally `The “I returned my iPhone 14 Pro and iPhone 14 Pro Max” Thread`. The title is written to explicitly attract those that have already returned their phones.
2. MacRumors users, as a population, cannot be assumed to be similar to the general population.
3. I posit that people who are happy with their devices tend to be on the forums before receiving their device, only to return again if they ever have a question about their device, or when the hype starts for the following year's iPhones.
You can't just invoke the word Science as if it were an incantation that magically makes your experiment hold water.