Trading can devolve into gambling, and sure there are likely more conservative trading methods that might not really be gambling, so there are not exactly bright lines in regards to the various categories, of investing versus trading versus gambling but they might sort of be on a spectrum in which many of us might not agree upon the thresholds upon which one of the practices might fall into being the next one.
Trading becomes gambling when someone who trades does not have knowledge about it and keeps on losing money. That means he is gambling with his money, but some people confidently compare these two things together, and I think they are not the same. However, the practices that can lead trading to gambling is when a trader keeps losing money and refuses to find a way to sort his problem out because when you lose too much and you are not making money out trading, that is gambling.