you buy when you were supposed to sell/wait, you will lose. this is not different from buying and selling physical goods in the market.
Only trading is different from buying and selling of physical goods in the market because in online trading, you have no idea of what the price of bitcoin will be in the next minutes making it very risky for new comers into the market. If you make a wrong decision like you stated above you run at a big loss. While in physical trading, you have high advantage of controlling the price of what you are selling. Because if you buy a snickers for $150, you can sell the snickers for $155 and whoever is buying will pay that amount, and if the first customer come in and price the snickers for $153, you will not sell until another customer is ready to pay $155 at anytime.
Currently, in my country the price of commodities are increasing and those traders are still making their profits because whatever amount that they buy it from the market, they will add their own additional money as their profit but in bitcoin market, you can buy bitcoin at $100 and want to sell at $105, but before you twinkle your eye bitcoin price dips, you might be waiting if the dip lasts long or goes deeper and impatient traders will sell of in loss to save their capital.
One thing that I want you to understand is that the possibility of you making good profit when you are waiting, buying and selling to wait/buy/selling is lower compared to an investor who is only focused on buying continuously every week without stopping using DCA will be. Because waiting is a waste of time and selling is also a waste of time because if bitcoin price goes higher after you have sold, you are in loss or you keep waiting again slowing your opportunity of acquiring and building your bitcoin investment portfolio for the future.
However, one can still directly gamble in trading if they do not know it but just forcing things. You can imagine the person who was not sure of what the market would do, instead of waiting for a clearer signal took a position. Such a person is actually gambling. The same goes for those who did not analyse the market but still opened a trade. This could be funny to you but some people do it. To crown it all with another gambling in trading, the main aspect of trading that is similar to betting/gambling is called Options trading. Anything outside these two examples when the trader is acting professionally is Trading which has every distinction from Gambling.
I am happy that you admitted that trading is gambling to novice of people who only have the basic knowledge of trading. This is where the point lies, it is a wrong advice that a newbie who just know about bitcoin and loves to invest in bitcoin should go into trading when it will not be easy for him to understand a bit of trading at that moment with the unpredictable price movement of bitcoin, because he will run at loss since he falls under the category of your post that I quoted. Wouldn't it be the best for that new investor to start investing by buying bitcoin alone with part of his discretionary income for a very long time consistently and persistently because it is very easy to buy and hodli with patience.
You are a good trader does not mean that a new beginner will be a good trader. It is always good to guide new beginners to the right side so that they don't run at loss if they trade and think that bitcoin is a scam, but if you tell them to invest and hodli for long-term with their extra money will be better.