(Slight Rant, Honest Curiosity) What's The Point Of Trolling In Ranked?

As the title says, this is a slight rant, but I was hoping someone could give me some sort of answer to the question, because of all the years I've played, I don't understand why people troll in ranked games.

This isn't just coming off of a game where it happened and venting, it is an honest curiosity, because I see it far too often (even in winning games, on the enemy team, it doesn't matter). I've seen enemy junglers completely troll their mid laners just flash in to intentionally feed me a kill, then flame said mid laner in all chat. Seen support randomly come from bot all the way to top just to spam emotes at their own top laner, trying to steal their cs, and so on.

I honestly wonder, what is the point? Why go into a ranked game with the intention of throwing the game and putting people on tilt? I mean...someone put the effort in to bother getting out of bronze, but then essentially lose their own game on purpose. I've seen it happen without any provocation (no chat at all and still it happens for example). It just baffles me why you would bother to waste your own time playing. climbing, then trolling your team, knowing you are likely going to lose the game, and a high chance of getting punished after being reported.

If you've done this before, why did you do it? If you've had this happen before, why do you think it happened (happens)?