What is the best methods to protect altcoin from hacker?
Keep on the safest wallet like have 2factor authentication or wallet have a sms verification because before to withdraw or to transfer the wallet they have confirmation from us. That was a safest wallet ever, Many of hacker targeted a not secured wallet like MEW. (Myetherwallet.com) Because that was only using a private key. But its up to the owner if the owner are careless so they can gave his/her private to the scammer.
Thank you for this advice. SMS verification works great unless it's overridden by hackers which I hope won't happen. I don't think anyone can give scammers the key voluntarily. That's just plain stupid.