To give you one example: I've been active on one forum for almost 20 years and on another for approximately 10 (one is general forum and the other is IT oriented) , there are no signature campaigns or any other way to monetize your activity and yet again people are active and helpful. There are bunch of other forums with similar situation, people join forums for various reasons.
as you said yourself: "people participate in forums for various reasons" did you try to observe the reasons why several people are on this forum? look at altcoins section and Gambling section. we have to stop pretending that most people come here for information when this is not true. Most people come here to take care of their business (money).
However the true entrepreneur will use his signature to improve his own businesses, and not some other guy's.
truth! I am not a business owner on this forum so I rent my signature space and I came to the forum to take care of my business: trade bitcoin and altcoins and Hodl altcoins and bitcoin, participate in signature campaigns and do sports bets. it all involves money, which means I'm here for money. I won't be lying because those are the reasons why I am here.