Agreed, you can master trading in all different forms and not just one form. With the mastering of all types of trading, you can make profits on all the conditions of the market.
Trading is hard and by trying to master different types of trading, traders will have to spend more time, more money for experiencing these types of trading. As said, because of difficulty in trading, by experiencing more, they will possibly get more losses, pay more costs for their learning, not only for learning courses but for actual trading practice.
Trading is risky, and if you want to trade, trade with Spot trading type. If you are a good trader, this trading type is enough for you to get profit. You won't have to try to master Leverage and Futures trading types, if you don't want to lose more money for learning.
There are some traders that when the market is dumping, they don't know what to do but to act like investors and be waiting for the bull market before they can become active again.
To avoid this, traders have to use Stop loss or Stop limit order that can help them to execute these orders, to secure part of profit, avoid loss or at least reduce loss for them.