Why do you still play Halo?

A lot of my friends don't play anymore but I still feel driven to continue playing Halo. I still find joy in building multiplayer skill and playing new mods but sometimes I'm left feeling empty without any of my friends there anymore. This keeps bringing me back to the questions of why do I still keep playing and curious why others still keep playing? What drives you to continue even through the roller coaster of unmet expectations by Halo Studios and the long gone friendships. Do your friends still play or are you just playing alone? Am I just chasing the relevancy I used to feel when Halo was on top of the world and being good at it meant something? Am I just in a loop of mindless self indulgence chasing the nostalgic high I used to feel? Am I just in hopium, investing in a sunk cost, hoping that Halo strikes gold again? At the end of it all do I just enjoy playing games with friends and connecting and Halo doesn't really matter but just upholds my self esteem with the immense investment I've already made? Stepping away to other games would be losing that investment and going into something more vulnerable and new? So many answers and they seem to change with every turn of the day. So why do you still play Halo? or have you stopped and just check in every so often for the nostalgic feels?