Why Was Voldemort Evil

How did Voldemort become evil?

Riddle stunned Morfin and took his wand, went over to the Riddle House and, using his uncle’s wand, murdered his father, grandfather, and grandmother with the Killing Curse. Riddle covered up his crimes by altering Morfin’s memory, causing him to believe that he was the killer.

Why was Tom Riddle so angry?

Tom Riddle was angry when he found out about his mixed heritage, and as Voldemort, he would basically deny it altogether. Later in life, he would present himself as a pure-blooded descendant of Salazar Slytherin and publicly railed against those without pure wizarding blood in their veins.