If you have received the Instagram Most Worthless User Wall DM you have likely noticed the link is for “Ever feel like there’s too many worthless people?” to Off-Topic. You are likely Googling it just to see what shows up. Upon further research, we have found out this is an actual website message board post from 6 years and 9 months ago. The website is Gamespot. While the website is not spam or a hack, the message on Instagram is. You can find the discussion forum link here (this is safe to click!). Do not click the link in your Instagram DMs.
As with all the other Instagram hacks over the last month (Worst Wall and Most Annoying List), this is just a way for a hacker to get you to log in so they can steal your login and password. They will then try to use this for other accounts such as your bank account or credit card account.
If you logged in, immediately change your password and make sure to change any of the other accounts in which you had that password.