I've had Google ads running for a while (for guests only)
They were also on the Wiki - again for guests only, but the Wiki uses separate user accounts and is a bit of a pain to login to.
I'd say they were generating about $1-10 a month depending on how many clicks. Anyways, not a whole lot. The main banner ad had text stating that ads are hidden for members - the main goal for me was to encourage people to sign up. But I don't know if the trade off was worth it.
Decided to do my part to fight the enshittification of the internet
and remove ads completely.
Hopefully if anything this will keep guests sticking around the Wiki and forum longer and sign up because they love playing IVAN and enjoy what they're reading.