Thanks @gillianpearce, I will make a post soon on the numbers and will try to make it as easy and clear as possible.

The 10x self upvote in theory being the most profitable thing to do on Steemit increases as your SP grows. To give an extreme example. someone whith 15SP has a ~0.002$ upvote who 10x self-upvotes will actually decrease their earnings since it very much goes against the social aspect of steemit which will get them less upvotes from others (same goes for most accounts). If @steemit want to purely theoretical get more out of their steem power (44Million+) compared to a x10 self vote they would need to receive nearly 10.000$ worth of daily upvotes. So for them a 10x self-upvote would by far be the most profitable thing to do looking at it from a short term profit perspective. Again all purely theoretica, I would never advise anyone to do a 10x self upvote just to be clear.

So the bigger you are the more upvotes you need from even bigger accounts in order to do better than a 10x self upvote. The way I see it, this self-voting is one of the issues this platform really has to fix somehow. Bigger accounts also should have bigger responsibility and care less about their relative return. (I once wrote a post on that. (Relative ve Absolute Steemit Earnings)

The middle class also really needs to grow. These are the number of accounts at each SP level. (picture taken from this post from @beat-the-bookies )