Bitcoin isn't profitable its just a free coin so technically you are not making profit out of it, profit is gained through investment and on airdrop you just signed up then they will give you free coins. I joined so many airdrop from the past week and no one is distributing already but im hoping for free coins they are saying.
Bitcoin is a free coin and it is not profitable? correct me if I'm wrong I think you've mistakenly identified bitcoin from those free airdrop coins or tokens those coins are distinctive to each other so they have their own name, you can actually identify it from their bounty thread where you've filled up your airdrop entry, It is not a simple sign up agreement as you need to pass their rules in order for you to be qualified for the payment, their distribution may take place after the ICO or the bounty so you need to know and wait for it.