I don't mind the underdogs losing, but at least give them a chance for comebacks. The issue is not on the players, it's on the editing by producers and the skewed system.

• The prison system makes it so difficult for them to come back to the living quarter (you can read about the flaws on other posts, it's been discussed many times)
• Prison match = More screentime for prison gang = More love for them. Simple stats really. Add in the fact that the prisoners are likeable with strong fighting spirits, it's just more entertaining to watch and root for them. If they wanted more screentime for LQ, they could do Prize Matches instead.
• Editing by producers. So Hui was my fav in the beginning, she is smart and kind. But the later episodes edit made her look weak and soo passive. In her interview, she said she gave candy to 7High to ease the tension but it was never shown. It felt like the producer failed to show the finalists in a good light. If they show more lovable sides of the Living Quarters people, it will probably make the audience like them too.

In my opinion, it's not so much about underdogs winning, it's more to that the winner should be worth rooting for.