He is the guy who will survive prison, but never use those survival skills to break out.
Usually an extreme slacker does so to earn a paycheck while their energy goes somewhere else.
In a past techie life, I recall a Wally-character in my department. Useless at work, but aggressively sold multi-level vitamins to all he could corner.
Reminds me of someone once I worked with. When they gave him a document to check, he would get out the OED and meticulously check the meaning and usage of every word. Took him a day to get one page done, never mind the whole document. "It's all pensionable time," he said with a grin. After a week, the boss usually gave the document to someone else, who got it done in less than an hour.