As a trader, it's not good to rely solely on trading as your only source of income. Why? Depending solely on trading puts immense pressure on you to meet monthly bills. The consequence? You may find yourself taking unnecessary and low-quality trades.
However, when you have another or multiple other sources of income alongside trading, you can stay relaxed and have the mental comfort needed to make quality decisions. For example, you can be a trader and be a Bitcoin miner.
Something similar happens with Poker, it is better not to depend exclusively on it, especially when you start. In this is similar to trading, what happens is that there comes a time in some people's lives when they become so good and earn so much money that they decide to take the leap to become professionals. But for this you have to have your back covered, as to be able to withstand a year of losses, because the bad patches exist, in addition to some passive income and other assets help to tranquility and make the right decisions.