The reason for this has to do with ‘variable reward’. Specifically, the brain quickly acclimates to a constant stream of rewards and gets bored. By contrast, sp

The reason for this has to do with ‘variable reward’. Specifically, the brain quickly acclimates to a constant stream of rewards and gets bored. By contrast, spacing out rewards at unpredictable intervals is much likelier to keep the brain hooked. As someone else noted, this is the same principle that underpins slot machines.