Isnt there moderators to delete those investment links or simple spams? Its their job to make the chatbox or room on free of spams to have better or smooth experience into its users.
Depends on the site you're on. Sites like PrimeDice have lenient moderation while the likes of Crypto-Games have a strong moderation and sending something like that will get you a temp ban.
On the topic, you can't really call it a multi-player game if more than half of the players are bots from the gambling site itself. That's what my experience has been so far.