You say "should be to wipe everything". Why do you think that's the most important goal? I'd have thought the BEST hackers would ensure their continued control

You say "should be to wipe everything". Why do you think that's the most important goal? I'd have thought the BEST hackers would ensure their continued control of the system and ability to exfiltrate data without arousing any suspicion. A good virus doesn't kill its host, a good hacker doesn't nuke their woot.