I have seen icos that gave too much airdrops to the point of having so many dumpers when their token is unlocked and being traded on DEX's. The result, the price go below ico. You have to really think about this, when you join an ICO and want to buy/contribute, you must check if they give airdrops. After that you must evaluate or ask around or DYOR if their airdrop is too good to be true and just so many.