The private key of your wallet is a very secret thing not to share it with anyone. It is very important to know well about those things before investing in anything. You don't have to provide a private key to get the official airdrop, the main purpose of those who say to provide your private key is to gain access to your wallet. So be smart yourself and fu** the scammers.
There is no valid explanation by any developers that you should give them your private key, you do not know Cryptocurrency and decentralization if you do not know this.
There are two guides and mantra that every investors should know, and that is not your key not your coins and only invest what you can afford to lose, these are the two things that people should make a mantra.