Why playing Phase 10 make people so angry?
Unlike a similar card game, Uno, players can target one another in a more direct way.  This can cause players to feel singled out and targeted which may feel unfair.  Skip cards can be given to anyone which means that everyone can skip the same person if they wanted to or make someone draw card after card until they are so far behind there is no reason for them to continue to play the game.  This can be frustrating and cause players to lash out.