If you exfiltrated confidential data prior to tendering your resignation then no one remaining in the organization is responsible for your actions. It may trigger a policy review to minimize the exfiltration of confidential data, but no one remaining is accountable. Moreover, the exfiltration of confidential data will put you in felony land and your employer will prosecute. You're guaranteed to lose your new job too, and likely never work again.
No, what most employees do instead - for those who do these kinds of things, which is exceedingly rare - is destroy data. That is extremely damaging to an enterprise.
There are plenty of motivations to get your rear end away from the keyboard! Some are legally mandated, depending upon which industry you're working in.