I would argue he could derive tremendous financial benefit from posting here in terms of furthering his career, networking, consulting gigs, etc. I'm not saying that's the reason he posts here, but it is a tangible fringe benefit.
Here's a thought experiment- How much money would you pay, tomorrow, for patio11 to announce that all of his posts on his blog and on HN have actually been ghostwritten by CapitalistCartr. What if he said the patio11 profile was actually a sockpuppet account run by CapitalistCartr, and all of the respect he has built up through his hard work and posts would now belong to you?
How much would that be worth to you? $1,000?$5,000?$10,000? I bet that intangible, what accountants call goodwill, is actually worth quite a bit.