Another great example - dont bother if you do not understand this
There are just X number of players in K2. It is not something that counts if you win or not. Just be top X.
If you are in position x+1 you are not in K2.
If you win you can still get demoted
1) If you are close the demote line
2) Other players won more thus your relative position dropped
Example to keep it simple
You are in 4th place (1-4 stay, 5-8 drop) in 8 player Kyber 2
Each player plays vs other
You win player who is 8th -> you get some points
Player who is 5th wins 1st player -> he gets alot of points and gets ahead of you
As result 5th player moves to 4 and you move to 5 even when you won.
-> you get demoted as you are 5th.
This is easily possible as there are thousands of players in each league.