Well a nonzero (and possibly quite large) number of those are bots. OSRS is a fun game but it's design makes it very easy to make bots for. If you play for a while you'll see them almost everywhere.
It worked for about an hour before having the nasty habit of attacking monsters, chasing them out into the wilderness where you'd check in on your character and find him dead, barren, and lost.
These days there are bots who hunt other bots. People make bots which kill "reventants" in the "revenant caves" for valuable loot, there were so many bots there that people made other bots to kill these bots and steal their loot from them.
Its almost a cool emergent ecosystem, except it sucks for us real players.
