Most 60hz monitors will OC to 75-90hz so.. yea, high Hz monitors need to come down in price before I'll consider one as 75-90Hz is plenty for a silky smooth experience.
If you don't play competitive level games and all you care about is maxing your settings out at the highest resolutions these monitors usually aren't for those people anyways because they're also usually not IPS panels so colors can look off but what matters is response time and refresh rate
The issue is this - Can your rig achieve higher than 100 fps on the games you play? If yes and you are using a 60 hz monitor, then you are wasting the frames. Once you play on a 120hz or 144hz monitor you will not go back. It is just so pretty.
I want to say around 90fps is where I can't notice a difference anymore personally BUT I loaned a friend my second 144hz and traded his 60hz to replace my second screen and it feels terrible to game on.
It's not something that you'd notice right away but as soon as you look back at a slower monitor it's easy to see the difference.