It's a learning experience, telling them not to play ranked they will likely not improve as much because normal games gives everyone a bit more freedom to do whatever they want. However in ranked it is a more competitive atmosphere, it's like entering a boxing ring for the first time, and the next time you enter it you will have known what to expect and do's and don'ts.

Let them play. Eventually they'll just find themselves at the bottom of the ladder. Doesn't really concern anyone else.

Sometimes I wonder if bad players are aware they're bad or just annoying twelvies who yolo ranked

A lot of people think they're good, when they actually aren't

I play with my friends who are better than me and i keep up with them

but when i do solo-queue i'm always the one getting the most fed and trying to carry the whole team