a LOT of the losses can be traced back to some mistake YOU did, so don't be so quick at whining.
I can't count the times I've seen a bad player raging at his team. It's true, sometimes you can get terrible players on your game and it's hard to focus on your mistakes, but more often than not this is the exception. In the majority of games you could always have done something better and got a win. My biggest climb in ELO happened when I decided to adopt this mentality when playing mid: "screw it, I'm going to play Kata and if we loose it just means I didn't roam enough, didn't WARD enough (as mid!!), didn't kill their ad carry fast enough, didn't ping objectives for my team, in short didn't carry hard enough".
Don't get me wrong, you should duoq if you want, but to really improve you need to focus at your own mistakes.
I just played a game with Evelynn and we were 2/11 at the start of the game, our top lane diana was doing terrible up top and our bot lane vayne/lulu werent doing great as well, so i went roaming bottom all the time with the jungler so we could towerdive and instagib their bot lane or get vayne a kill, so vayne could get fed and we won eventually after a 60 minute game (in that game we were behind in around 4k gold ALL THE TIME but everyone knew what to do in a teamfight, so we won)
What i want to say with this is, in lower elo a game is not over if you are 10 kills behind because people are just not good enough players to hold their advantage. if YOU can do everything right (which is nearly impossible) you almost definately win since they will be raging at each other, and you show presence as whichever role you are, if you also do your job in a teamfight right you can singlehandedly carry a team if they actually want to win. (and there still are people who dont want to win, somehow.)
Otherwise just get a group of friends and play with them, that is definately more fun than with randoms.