The title of this thread is bit provocative, but the fact is that most people have a bad experience with airdrops. According to several airdrop hunters I spoke to, the majority ICOs don't pay out at all.
What's your experience with airdrops? Did you get scammed most of the times?
I think the 80% / 20% principle is well known. 80% of the work we do is empty, but we do it in order to receive awards. And the remaining 20% really bring rewards. No one knows which of the projects will bring us income.
I generally do not participate in drops. I think this is a waste of time. It is better to participate in the bounty company.