Scammers are abusing hot topics. Everyone is reading about the success of UNISWAP and its upcoming airdrop, so who doesn´t want free money? People are greedy and they will not do research to find out if the airdrop is legit or not 
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That's right, sometimes even smart people can be fooled just because of their greedy "thing". Many people still lack self-control so they can't think clearly or just do their own research. Even though they do little research is more valuable than having to lose assets due to carelessness..