RP points is depend on the amount which you stake on your predictions I don't think it is impossible for any person to achieve the high rank if he get started from zero too. If you want to gain more points than you should have to deposit more STX tokens to take maximum advantage from this platform.
Yes, it is true that rp are reset at the start of every Stox cup, It is also true that as you add more Stx to your account, you can more easily d well in the Stox cup and winmore prizes as a result. But there are elements of skill to the game.
As more people adopt the Stox platform this will mean less disparity among participants in my opinion.