For example, my total points are 5559. With the suggested option, I could bet 50% of my total points, which would be 2779 (rounding down). MadMarx, if interested, would also bet 50% of his points, which would be 13378. The Czech would bet 50% of his points, which would be 6291, and so on. MadMarx would have more points in the total pot, but his investment relative to his wealth would be equal to mine, The Czech's, and everyone else's. Ideally, under this option, there would be a minimum required investment (X) that could be typed in, so that everyone has to bet at least X points, which would help maintain a minimum level of commitment from everybody (50 point buy-ins might be possible, but wouldn't necessarily be appealing to someone like Marx, so this minimum investment option would alleviate that).
However the game ends, it would pay out no differently than the current system--in other words, a winner would take all under WTA or the points would be divided under PPSC, or divided equally under a draw amongst the surviving players.
I think this would put an exciting twist on high-stakes games across the site, enabling the creation of games with incredibly high payouts without excluding underdogs who don't have 5000 to bet on a game.