Okay, I don't know if I'm just being over dramatic here but I've been feeling really left out recently with my group of friends. 

There are around 12 of us and we all became friends through playing Counter-Strike. There are about 6 of us who play the game a lot (in the context of our group) and the other 6 are either: just play sometimes, don't really take the game seriously or are busy with school work or other activities. So, there are 6 of us left that play the game a lot then the other 5 (the 6 people who play a lot but doesn’t include me) started a "team" which doesn't include me, which includes making a steam group, group chat on social media and talk within themselves which makes me feel really excluded. I thought about reasons why they would leave me out, I thought that skill (in the game) could be the reason but I that's impossible since rank-wise, I am the highest along with one of the 5. They even joined a LAN tournament without me even knowing and I was still playing with them but then I noticed them being secretive about this new group.

AITA for thinking this?

Also, what could be the reason for me being excluded?