I don't think you mean "negative balance", since nobody has a negative balance.

Do you mean accounts with a negative profit? If so, you are creating an incentive for people to create new accounts whenever they have a negative profit. It wouldn't be in the player's interest to try winning back their loss on that account - better to make a new account and play there.

Finally, how do you suggest that staking rewards are given out? Should 50% of every stake be split between all the accounts with negative profit forever?

The problem is that the investors are able to divest and earn the full 100% of their staking rewards. If they only got 50% of them by investing at Just-Dice, it wouldn't be worth their while being invested. Certainly the negative effect on investors wouldn't be offset by the small positive effect on players. Gamblers won't be impressed by being awarded a small share of 50% of 1 CLAM every minute or two. It's too small to make any difference to them.