If I have a few mins to kill during the day (usually when waiting for ETH/BTC to hit the exchanges from my wallet) Ill sign up for an airdrop or two. Most of the ones that I have either haven't hit exchanges or are worth under $1.
TRON (TRX) was the first one for me that actually did something.
500 free TRX peaked at ~$30 and is currently worth ~$19
HODLing!
Mine is PolyMath as they give out 250 POLY tokens to users who completed the KYC, i managed to grab hold 250 Poly tokens myself and very happy with it, 1 token cost 0.85$ right now and total value is 213$ super happy about it, a good right move for myself
