Good Friday is probably the only event in the world that celebrates the death of a harmless person, calling it "good".
People might be more willing to cheer for the death of an evil person, but a harmless one?
Of course, Jesus was not actually harmless to all, as he questioned, criticized, & sabotaged the powerful religious authority of his day.
Jesus threatened the most respected & highest official in his community, the High Priest Caiaphas.
As a result, the authorities plotted & had him captured, prosecuted, & sentenced to death.
However, on Jesus's own decision, he didn't defend himself at the trial. He desired to be sentenced to death, believing that that was his destiny & there was a cosmic purpose following it. Thus, he was crucified.
His death left his followers confused. Many of them went back to their business as usual, defeated.
Then some time later, his followers regrouped and began celebrating his death as if it was a victory. They came to understand why Jesus desired to die. They saw the cosmic significance attached to it. As one of them later wrote:
"Very rarely will anyone die for a righteous person, though for a good person someone might possibly dare to die. But God demonstrates his own love for us in this: While we were still sinners, Christ died for us." (Romans 5:7-8)
The dramatic shift from being defeated to being victorious owed to the followers' experience of Jesus being risen 3 days later.
That is why this Friday is "good". Blessed Good Friday to all.