For any given game, ranked or not, realize that it is actually teams that win or lose.
We want to believe that great things come from hard work, from careful planning, from directed action. But this, in part, makes us underestimate how much of life is driven by luck:
“The point is simple. If you look at all the really important breakthroughs made in any field, what you will find is that the unplanned, unintended or fortuitous connection plays just as great a role as the planned, the processed and the organised. This is why, fairly early on, Microsoft placed whiteboards along the corridors on the Redmond campus; for they found that the accidental meetings which took place in hallways were in fact more productive than the scheduled ones which happened in meeting rooms.”
I'm not talking about Klepto or Zoe RNG, but rather the champions that are chosen and the players that are behind them. Unless you roll with a 5 man premade all day, you don't have any power over your team mates and you sure as shit don't have any control over your enemies, ever.
It's really quite a feat for ONE (i.e you) player to make a game impossible to win, but it's trivial for 4 other players to do so. Realize that there's a line in the sand that divides a massive amount of LoL players and virtually all gamers in every game ever made. Some people will adhere to the basic fundamentals of going after the win condition, and some people will fap about and waste time on BS that doesn't really matter. In Magic the gathering, there's johnny's who build overly complicated combo decks, timmy's who build decks out of big rawr creatures, and spikes, dudes who actually like to win.
Same damn thing for LoL, realize that sometimes, your team honestly, despite the whole point of the game being trying to win, sometimes.....your team really doesn't want it. They'd rather PvP or do whatever they are doing. It's mind blowing that people would even play if they don't want to win, but it's something I think a lot of people have to learn to accept, including myself.
edit i type too much lol