A brief look at the history of Bitcoin and the cryptocurrencies reveals why is dangerous to leave your crypto funds in an exchange. Since 2011, over $1.65 billion worth of crypto assets has be stolen, and the the numbers are accelerating on a daily basis.
Keeping your digital asset in an exchange wallet it comes with added risks. So storing your cryptocurrency there for a long period of time is not a good Idea.

There are many malware variants that infect computers, monitoring every key you press on your keyboard; they are called KEYLOGGERS. Some enterprising security researchers have discovered that with certain wireless keyboards, they are able to bypass the computer completely.
According to there experiments, they where able to scan the radio signals passing through the keyboard and the computer - from 50 meters away. When they analysed the data it was found that many keyboards were sending that information in a plain text- INCLUDING PASSWORD AND PAYMENT DETAILS.
The good news is that most wireless keyboards now use Bluetooth which automatically encrypts keypress data making it almost impossible to intercept or read.