Who told you forum and social media is useless? I think your marketing materials is not attractive. Another factor is the niche, if you post bitcoin related ads to food, or celebrity no one will click your ads.
Which is the best way to promote products or refferal links? Social media and forums is total shit,no one interested in this.
Agrees with you, forums and social media is very useful for promotional products and links. There are 2 reasons why people are not interested in this, the material is unattractive and wrong strategies. If promoting a product or link that is not interesting of course it will be useless, so try to make interesting promotional materials. Wrong strategy and that's like you say, make a post about a product or link related to bitcoin to food or to a place that has nothing to do with bitcoin and it will also be useless. Try to post in the appropriate place, will definitely attract people.