The issue is clear here. It's not Pyke - it's the people who still have that mindset of "all kills go to me or I can't/won't carry". Those people are typically low in general skill and game knowledge, and think that, as they're a carry (or they may want to be a carry), they need to have all of the available resources allocated to them.
The thing they need to learn is that "kill-stealing" isn't a thing. Sometimes your Support (or someone else) is going to be the one to get the last hit in for whatever reason - ADC is too far away, cooldowns are still going, or some other asinine reason. They need to get it in their head that there's no "I" in "Team", which means that sometimes, they're gonna have to let other teammates get some of the resources. Whether that's Supports/other players getting the kill, or Supports taking a bit of CS while they're away.
The biggest hurdle for it all though is that, for many people, vanity is one hell of a roadblock. It can take a helluva long time for people to realize that they can do just as well without direct kill gold as they can with it.
Sorry that you had to deal with that Xayah, and moreso that their ego cost you the match, but hopefully there'll be better matches ahead for you.