People bot because 10 marks all day long will net them a decent amount of marks per effort (zero) each day. If you increase the rewards for a loss, you will increase the incentive for people to bot resulting in more bots.

The best idea for increasing rewards for those currently gaining at a slow rate is to make a change to the system so that those that queue in 3 man premades are paired against other premades. The win rate and marks gained for those now doing solo queue should increase significantly with this one change.