What the article is just saying is that trading risk is the same as gambling risk if only 3% of traders are making money while 97% of are losing.
Can this be true?
Yes, it can be true. I have some trading experts in my favorite list, they hardly post PNLs these days because the market is not favorable to them this time and they hardly share signals more often than they use to because the market is not stable, and even the signals they share is not going as they wanted just that it do give profits after some times.
There is a very high risk in trading that is similar to that of gambling because future trading is very risky, and one can easily get liquidated unlike spot trading when you can become a holder till the market becomes stable or till you are in profit. The same way you lose in gambling when you make wrong predictions is the same as way you lose in trading.