Getting posts to the front page is big business. A launch via ShowHN that hits the frontpage is easily going to get a business going with signups and users that a flop of a post that never gets seen, won't. But you can't simply make 1000 accounts via the same IP, wait three days before using them, and then upvote your story. That'll set off the ring detector and your upvotes won't be counted and you'll never reach the front page. So you buy aged accounts with rich comment history to do so instead. Not that I have any proof of this happening, but the motivation for it should be obvious.
I would encourage you to spend more time submitting posts (looks like you have none on this account), and browsing https://news.ycombinator.com/newest and seeing what fails to gain traction and get upvoted, to disabuse you of this naive notion. That the frontpage is so fickle is such a known problem that dang created* the Second Chance Pool** to give good links another opportunity to rise to the top.
