Turn the model around so that everyone benefits when people try to acquire more than they are given and give nothing for nothing.

Remember the way things were around here before the rep system?
People earned money for their work, and some built bots to do tasks like welcoming new users.

The only reason people were really upset about the bots, is that the bots allowed their owners to earn more money than they could because they had found some loophole that allowed them to have multiple accounts while most people couldn't. This allowed them to get around artificial limits like posting limits and enabled them to earn far, far more. I mean look at @wang he became a whale literally by saying hello and giving good advice to new users.

If you take away the artificially imposed limits in the system, the system will work to find it's own equilibrium.