Those fans were ready to erupt with cheering their team until the last 10 minutes, if the team showed they have a heart and they care... even just a little bit.
The team totally betrayed their hope and decided to stop trying in the 3rd, as if they know the game's already over.
After witnessing such a bad on-ice product year after year for almost a decade, I think fans have all the right to be pissed and show their frustrations.
At least it means they still care about their team.