I honestly think you're making too much assumption right now.
- 'CubeCraft loses players due to their high prices.'
So if people don't buy a rank because it's too high priced, they immediately leave the server? Why wouldn't they keep playing without rank?
- 'If ranks become cheaper, more players will buy a rank, which causes more players to join CubeCraft, which makes CubeCraft able to spend more money'
So your logic is: Ranks become cheaper -> more players. Like I said before, why would players only play on the server with a rank?
But I admit, once people have a rank, they will spend more time on Cubecraft because of their rank.
Your last conclusion however: 'makes CubeCraft able to spend more money', I think that's a huge assumption. Who says the new players (who occassionally buy a rank) give more money than the loss of money because of the cheaper ranks.
A normal company would have to spend a lot of time and money researching the results of a price change. That's is even harder to research for a Minecraft server.
(In the economics, this is called Elasticity: The change in demand regarding a price change)
- I hate seeing a server like this die. Come on, grab your chance while you still can!
As I said, how do you know it will have good results for CubeCraft?
- If you have more money you can develop more (good) updates, so that this server gets even more players
Basically the same as your second point.
Don't get me wrong though, I do agree that the prices are too high, considering they lost a lot of voting option at removed games.
I personally wouldn't spend a dime on a free server, but that's me being Dutch lol.