Never click on any unknown link. These links are promoted by hackers in different ways. They send most phishing links via email. Don't join any giveaway that wants your private key. I saw that by attending the giveaway, many were victims of hackers. Simple.
It is true,
Most crypto users become a victim of hacking because of this trick. And since this is free they just click the link and log in their wallet on the fake website that hackers made. That's why it is better to investigate if the website is legit first and see for yourself if it is really a giveaway. Also, don't just easily log in the wallet to being a victim of hacking.
I was almost a victim of this, but except that it was an airdrop email to me. People should be aware that just because the site is quite fancy, doesn't mean that the people behind the monitor of those sites would do you any good.
This is one of those sites that could've probably successfully baited 70% of newbies in altcoin airdrops, because one of those site claims that they're in partnership with MEW and it is gonna require users to put in their wallet into the site for the tokens to be received.