-Do you consider this trader correct?
In my opinion, there is nothing wrong with what he said.
A trader, moreover day traders, will always trade every day in order to take profits by utilizing every up and down price of the coins that they are trading. That is why they need certain analyses of the charts and indicators. I know that it may not be all of them, but most traders may do the same.
Many traders also trade in the future market or with leverage, so they can utilize the up and down by positioning Long or Short position.
This is coruse, not easy, very risky, yes exactly. But, this is what a trader commonly does in order to take profits and earn money in every condition. For, not all people are able to do long-term holding. Some prefer to trade daily to earn profits.
is there any guarantee to always make a profit?
of course not.
But, commonly a trader will know what to do when to do it, and how the ways to make higher profits than its losses. In one day, a trader may experience both losses and profits. This is very common to them.
However, if we are not good traders, newbies, or not ready with the market changes, it is better to play safe and do what we are able to do.