I'm sorry that you were denied access, gatekeeping is real, especially in STEM fields.
I just want to offer that not everyone doing a PhD is doing so for reasons of money or prestige, and not all of them are coming from money or prestige. And the gatekeeping doesn't end once you get in, either. If anything it intensifies the further along you get, and by orders of magnitude the more your circumstances don't parse to something like {age = <30, marital_status = single, kids = false, parental_income = upper_class | middle_class, parental_support = true, needs_to_work_to_survive = false, parent_has_bachelors = true}
I just want to offer that not everyone doing a PhD is doing so for reasons of money or prestige, and not all of them are coming from money or prestige. And the gatekeeping doesn't end once you get in, either. If anything it intensifies the further along you get, and by orders of magnitude the more your circumstances don't parse to something like {age = <30, marital_status = single, kids = false, parental_income = upper_class | middle_class, parental_support = true, needs_to_work_to_survive = false, parent_has_bachelors = true}