That is the basic thing and every trader must know it better before taking proper start in trading. You must not put everything in one investment. Rather divide and keep every portion in different chores. Like if you have an investment, divide it and keep 50% in bitcoin, 25% in altcoins, 10% in bank for saving and other for daily needs. These ratio may vary person to person.
Absolutely agree. It is dangerous to use all you have for every kind of trading. Not only in cryptocurrency.