0 used to mean "it's not important" and "I don't care":
So what if I'm 35 and I'm not married - I lead a perfectly fulfilling life!
"Andrew won't like it, you know." "So what? - I don't care what Andrew thinks!"
1 infml it is of no importance:
"We are not supposed to be here." "So what?"
NYA ORD
European
May 10, 2021
DAGENS ORD
Shimmer
so what?