The reason people bet in multiple is to increase the winning potential and nothing more. That is the reason and they understand the risk that the chances of all the games being successful is narrow but that does not stop them to complain, regret and cry (especially when it is big potential) when they lose it 
The aspect of single bet is people don't go often with it because the odd is small and they will need increase in stake for the potential to be substantial but the risk is still there no one is guaranteed.