This is a stupid question. Why Altcointalk wasn't active a few days ago? The answer is simple. There were no signature campaigns that paid a good amount of money. Why it's becoming active again? Because there are some campaigns. Of course, the market economy helps forums to remain active. Do you think everyone writes for money? NO. Not everyone. Moreover, even when people write for money, sometimes they add value to your thread. It's easy to find who is writing for money only and who is not. When you see people write only on some specific boards where their campaigns ask to post, (Gambling for example) it's understandable why they do not show any interest on the other side of the forum.