Many people regret that they did not buy BTC while they first knew about it. For some, they did not sell BTC while they could. 
For me, I got MWC & HEX for free from airdrop to BTC HODLers, but dumped them before they peak. I could easily make 10x of my existing BTC, if I held them strong.
What is your Biggest Crypto Regret?
In Indonesia Mb8coin were sold in own fiat currency. Later Coin price was so high. These couldn't be good example but you should accept all of these situationFor me, I got MWC & HEX for free from airdrop to BTC HODLers, but dumped them before they peak. I could easily make 10x of my existing BTC, if I held them strong.
What is your Biggest Crypto Regret?