“I haven’t seen X, therefore it doesn’t exist.”
Absence of evidence is not an evidence for absence of something.
I haven't seen leprechauns, at least not without the aid of xiao ren ren mushrooms, but I'm still pretty sure they don't exist.
I haven't seen leprechauns, at least not without the aid of xiao ren ren mushrooms, but I'm still pretty sure they don't exist.