It looks like a fun idea, but I can't see it working.

The only ones that stand a chance of being placed are those that invest the max allowed (5BTC). That means only 5 places (+1 random) payout an amount higher than their investment. If it was all 5BTC players, there would be 40 players, yet only 6 will be guaranteed a profit, meaning 85% of the players would lose, and most would lose a lot.

This may appeal to gamblers, but considering most dice games payout over 99% of the pot, and this only pays out 86%, it doesn't look like a good deal.