Day trading is not a scam, per se, but it IS arguably high-risk.

Your success as a day trader will depend largely on your ability to assess context and circumstances, make accurate predictions about the markets, and execute trades flawlessly. If you have a strategy with even a slightly positive expectancy, then you stand a chance of making money as a day trader. But if your strategy is flawed or you don't have the discipline to stick to your plan, then not only are you unlikely to make money, but you're likely to lose money instead. So above all else, do your research before getting started, and make sure that you have the requisite skills and experience.

Like gambling, there's no such thing as a guaranteed winning strategy in trading or any other form. However, as I mentioned above, if you have a well-thought-out strategy with an expectancy (the percentage of times your strategy will produce a profit vs a loss) that's even slightly positive, then you theoretically have a chance to make money over time.

Of course, there are no guarantees in life and there's always the possibility of incurring sizable losses if things don't go your way in the trading realm. But as long as you're aware of the risks and have carefully planned out your trading, it's possible to be successful with day trading. Just remember to always trade within your risk tolerance level and never put in more money than you can afford.

Hope it helps.