There are lots of studies about emotion in trading. Fear of missing out, greed, etc. are very common causes for people to make mistakes while trading. No matter how experienced you are, you will eventually be led by emotions and this might make you lose money, so you have to prepare yourself to do it as little as possible and to control yourself better or you will lose more than win.
Cryptocurrency is volatile! There is always the chance that the market will crash, or that you will face some other catastrophe. Cryptocurrency isn’t a centrally controlled and regulated fiat currency. If you lose a coin, or someone cheats you, or your account gets hacked, there is nothing you can do about it (which is one reason why you want to have 2-factor authentication set-up).
EDIT: #10 Bonus (Suggested by @kerstenwirth ) — always check the ticker symbol. Ticker symbols are not universal, and may vary from exchange to exchange in rare cases. Those cases, though, can come back to bite you. For example, Bitcoin Cash trades on some exchanges as BCH, while it trades on others as BCC. BCC is also the ticker symbol for BitConnect, which was recently outted as a Ponzi Scheme. If you bought BCC under the impression was Bitcoin Cash, you would’ve lost a lot of money.
Only invest what you can lose. During the recent crash in January 2018, hobby-investors got burned. Reports of frustration and losses came at the cost of broken monitors, smashed laptops, and heavy monetary losses. While the rules are in more particular order of importance, it’s safe to assume that this is the most important rule, the rule to rule the rules. As soon as your money is converted into cryptocurrency, consider it lost forever. There is absolutely no guarantee you can get it back. Losses don’t simply come from dips in the market; extraordinary factors such as hacks, bugs, and government regulation can mean you’ll never see any of your money again. If you are investing money you can’t afford to lose, you need to take a step back and re-evaluate your current financial situation, because what you’re about to do is an act of desperation. This includes: using credit cards, taking out mortgages, applying for loans, or selling everything and traveling the world (as glamorous as that sounds).