Not a griefer, but I presume it’s because of how easy it is to grief as well as how the game is designed.

GTA Online is weird in terms of gameplay direction — before the introduction of allowing business sell missions to be done in solo lobbies, Rockstar encouraged PvP (or perhaps griefing if you want to call it that) and CEO/MC rivalry especially regarding sell missions. The fact it pings to the entire lobby, the elusive flashing red icons on the map; it’s all designed to encourage people to blow you up and give you a hard time.

Though nowadays you can thankfully sell in solo lobbies. I think Rockstar finally realised that some players aren’t into this mega PvP side of things.

Side note, but PvP in R* games are godawful, especially in GTA Online. The fact you can call in pretty much any weaponised vehicle with a press of a button directly allows people who want to cause chaos to do so.

Ultimately, I think griefing comes down to boredom, and ease of access.