Make bitcoin paid signature campaigns the only acceptable campaign on the forum and the spam level will reduce by 90% or make Bitcoin & Ethereum. (BTC for Bitcoin service section and ETH for Altcoin service section). Now to get a 99% reduction of spamming, implement a new rule that get your signature wearing privileges remove for 3-12months based on your level of spam, when you're caught shitposting (having a certain number of good spam reports against your account). I'm positive a decent number of users would change their posting habbit just to avoid getting banned from wearing signature ads.

The fact is, we're in a time, were people tend to earn from any social media platforms they're on. We shouldn't denial them that privilege unless they're caught abusing the privilege.