11. Did not take chance to buy Bitcoin cheap.
Maybe in 20 years new Bitcoin users say it was a mistake they did not take chance to buy Bitcoin at $100000.
12. Bypassed good and secure Bitcoin earnings.
13. Baught pizza with several Bitcoins
14. Cloud mining
15. Ponzi schemes
I'm sure most of us have made a lot of mistakes in the past. The best thing is to learn from them and try to make the best of it going forward. And you can still make a profit even if you lose money on mistakes as long as you keep working on it.
Try to learn from the mistakes made by other people. Read about it.
I have not lost a large amount to hacks (knock on wood). In the past I was lucky, now my security is improved to make it less likely.