[flagged]
"Please don't post insinuations about astroturfing, shilling, bots, brigading, foreign agents and the like. It degrades discussion and is usually mistaken. If you're worried about abuse, email hn@ycombinator.com and we'll look at the data."
https://news.ycombinator.com/newsguidelines.html
The odds that a Hacker News user who has been here literally 19 years and submitted over 4,000 links is some sort of marketing shill seem rather negligible. You could have figured that out yourself based just on the public data.
(1) You don't know that anyone was paid to post. This is entirely an assumption, one that internet users are far too quick to make.
(2) Therefore, it's against HN's rules to make such insinuations in comments. Please review the rules and stick to them: https://news.ycombinator.com/newsguidelines.html.
(3) Even when an article can justly be called an advert, it doesn't automatically follow that it's off-topic for HN. Most adverts are off topic, of course, because they aren't intellectually interesting. Intellectual interest a.k.a. curiosity is the only criterion for what's on topic here—again, please see https://news.ycombinator.com/newsguidelines.html.
3D-printed, alcohol-powered, Einstein-Szilard absorption refrigerator https://youtu.be/doZ5e4YVdEs?si=WNiw0_R7efE6M_jM