Romans 6:16 Don’t you realize that you become the slave of whatever you choose to obey?
Yes, that is true. You're a slave to the Watchtower. The Watchtower instructs you to hate the holidays, and so you do.
How so? Had you been a JW before 1928, you would have been celebrating Christmas as well. Based on your theology, celebrating Christmas wasn't a deal breaker for Jesus when he selected the JWs as the true religion in 1919. By enforcing a rule like this, JWs are acting like the unforgiving servant from one of Jesus's parables (Matthew 18:21-35).
As for us, once we leave, we have the choice to abide by our own conscience! For the last 10 years, I chose not to have any lights on my house. This year, I am choosing to have lights. It's my choice. The "world" doesn't care about it. All my "worldly" friends don't care about it. One way or another, my friends respect my choices. So, who's a slave to whom?