You played that great match, the team score was 50/37, your team played well, and victory.
Then you go tell that to a friend. "Hey bro, check this" *shows the screenshot* "I won this match today, really awesome".

OK, you played well, but what happened to the rest of the team? You got 50 kills and your allies died 37 times? Of course not, everyone did their best to win.
There are times that you kill enemies and your team just feed, but thats not the situation here.

Why you say "I won" instead of "We won"? Its a team game, many players do their best to win, and you want all the credit for yourself?

Next time you achieve the beloved victory, tell your friend "we won".