1. Not Backup Key
2. Electricity Billing Mining More
3. Lunes In Phishing Sites
4. Buy Coin With Rumors
5. Create a weak password
6. Steal With Stealth ICO
With cryptocurrency, no bank or other institution or regulation will protect you in the event of a loss.
Probably the worst mistake anyone can make is getting hyped into business, being too confident, and then just jumped right away without even learning the pros and cons of bitcoin...in short lacking of knowledge will simply put you on the verge of crisis.
It seems to me that one of the biggest mistakes that can make you poor is the wrong choice of the altcoin. really, do not believe the rumors and be careful when picking an alt.