It is just rough estimates based on the table Unity has on their site.
The cheapest is like 1 cent per install. But it starts at 20 cent. Granted, there is a threshold, but what aspiring dev would not want to have success in the future. So even amateurs will be wary what engine to learn for future success - even if that success might not come.
The pricing model they plan to have is especially detrimental to the pay-what-you-want model popular on itch.
So if you had a very popular pwyw game and had the gigantic success of making the threshold, what would that boil down to? You used Unity personal of course, because you are one of those indie devs that have no money. And that one stays at 20 cent. So you have 1 000 000 downloads a year of your Unity personal game. 20 000 of the players tossed you a 10er for the game. Bringing you above the threshold. Your payment due to Unity? 200k. And if you have a single download more, now you lost money by having a popular game. Maths is fun.
