Bruce Banner canonically has 7 PhDs and honestly the fact that he periodically turns into a giant green ragemonster after spending that much time in academia without tenure is the most believable thing in the entire Marvel canon.
They might if they're trying to keep delaying student loan payments.
I tried to go for two back in the day but the university told me to just choose one. Still, I did eventually get formal postdoc credentials (the local equivalent to the Habilitation of the German academic culture, at the level of associate professor in US terms) and have worked as a university lecturer in both fields, and been the president of a learned society in a third unrelated one. Seven completed doctorates is a bit on the unbelievable side, though, even with high intelligence and ADHD.