Why am I so upset over the death of a man I didn't even know?

A very similar thing happened to me(except to a seemingly lesser extent) and I'm a straight dude. I was initally pretty sad about him dying(he was one of my favorite actors growing up) but I was just like whatever life sucks, wish he was still around cause he seemed like one of the only genuine "A" cl actors . Then after watching The Dark Knight I was like oh man he played a great joker, it's such a shame he died, rubuhbuhbuh. About two days after that I wiki'ed him and read about his life. Turns out he was born on the same day as me and like me was a big chess dork. I then went on to read how he would frequently play chess in union square park, and was about to direct and star in a movie called The Queens Gambit, a movie based off a book that I really liked and would have really liked to see him star in, after all this I was kinda /sigh. So yeah It really sucks that my now favorite actor who I had a good amount in common with is dead, but at least he brought the quality of character in hollywood up for the time he was around, and I was able to enjoy his movies.