I believe other people are trying to say that there is a risk, and the risk you are willing to take is like when you are gambling. That's pretty much the resemblance between the two. They are definitely different, but in terms of risk, they are the same.
I prefer trading to gambling because you have more control over risk management, stop losses, and take profits intact compared to gaming, where you depend on yourself. Sometimes, if you are in the moment, you have difficulty controlling yourself and should be honest.