I know projects which were carried out by airdrops about a year and at the same time the price of a coin constantly grew up. So everywhere you need competent marketing.
And you can name the specific name of the projects that were free to hand out coins to users and the price of the coin was constantly growing ... sorry, but it sounds absurd.
There were several such projects. Read about the project DeeoOnion, who spent his airdrop from June 2017 to may 2018. The price starts from a few cents and at the end of airdrop cost about $ 15.