Gaslighting and Catfishing exist in offline life. We just recognize these behaviors as:
Being a fucking liar
and
Being a fucking goalpost moving liar.
The ease of the Internet enables these behaviors to become far easier because the catfisher and gaslighter have nearly absolute control over their personal information online. If you want the details to fit your narrative, you simply don't publish contradictions or scrub them prior to discovery.
It's tougher, in general, to pull a long con gaslight or catfish offline. The proximity and the easy ability to weed out false information sorta makes it impossible to keep up ruses the likes of which are seen online.