Of all the curses you could have placed on you, uttering true prophecies but having no one believe you might just be the worst. Let’s say you knew a pandemic was coming, but everyone you told said it wasn’t real - now you know how Cassandra felt.
After a smitten Apollo gave Cassandra the gift of seeing the future as a way into her heart, she still rejected him. Enraged, Apollo added a torturous caveat to the gift he had bestowed upon Cassandra - that nobody would ever believe her. After getting gaslighted on a mass scale, Cassandra foretold that Troy would fall - she even predicted the whole Trojan Horse method. Of course, no one listened, and the city fell to the Greeks. It was probably the single greatest Told You So moment in Cassandra’s life.