How the *profanity* can I improve?

I feel like I'm doing decent every single game I play. I honestly do not understand how I can do any better, when there's constantly 2-3 salty people that aren't playing well (1-15, 4-14, etc.). I'll win lane 3-0, but eventually master yi, who's 17-0 will come and rape me.

I don't flame either. So don't come here and tell me that they're playing bad because I'm telling them how stupid they are. I always try to be supportlive, but anything I do just makes it worse!

The negative attitude that these people have also makes it so insufferable to play with them. They'll join the game saying ''heyyy, imma troll this game'' because our botlane wanted to be a bit creative with their picks. Once in a while, i'll try to say something like: ''hey dude, you're a bit low on farm''. The answer is, immediatly: stfu you %%%%ing noob you're toxic''. And they run off to all chat telling my enemies to report me.

And honestly, this is every. Single. Game. Ever. Sure, people can have a few bad games, but if I do check their statistics - guess what? They have at least 15 more deaths than kills in all the previous games they've played, except a few.

I've tried playing different roles, i've tried to talk less, talk more, focus more on farming etc. but nothing seems to help, because if I don't have 20 kills within 15 minutes I won't be able to hard carry, which leaves the outcome to my team.

Does anyone have any tips to what I can do?