I play XIV for the same reason I play other videogames, and that is they entertain me and allows me to have some fun in my otherwise normally dreary days.
Reason I love XIV is because its an MMO which always evolves, and there are people to interact with and such.

Most games like Call of Duty, Overwatch, LOL, Shadow of Mordor, Street Fighter etc is fun for a few hours and I dont play them again for months or sometimes even years as they dont have any staying powers at all

For XIV, I really like supporting devs that genuinly seems to be open and honest towards its playerbase, content is nice and constantly paced, main story in ARR HW and SB are really good, and I cannot wait to see where Stormblood takes us. Most people in XIV also seems way more mature and friendly compared to the normal toxic ones I meet in WOW and other MMOs. And the friendships I have made in XIV is also a huge reason I play XIV, as I can have a dreadful day in RL, log in and just hang around in FC chat and teamspeak and my sad day melts away