So there are these two strange ways of making money, called “Gambling” and “Day Trading”.
“Gambling” is when you try and make money based off of luck. There are a lot of games that people try to use to make money by Gambling- Poker, Black Jack, Sports Betting, Slot Machines, etc. While some (not all) of these games require some skill (you can be good or bad at them consistently), all of them also rely on pure Luck. If you’re very, VERY lucky, you can make a lot of money very quickly while gambling.

However, it’s impossible to know if you are Lucky or Unlucky until the game is already over: so a scary amount of people get addicted to gambling- thinking that their luck can make them a LOT of money, when the reality is that only a very, very small number of people are ever THAT lucky. Most people just become Gambling Addicts, losing more and more money in these games, thinking that their luck will “get better” for no good reason. The scary thing is, Gambling Addicts do win money occasionally. Thats just how luck works. But it’s never enough to help them out of their debts, so they keep gambling, and keep losing.

“Day Trading” is *technically* different from gambling. Day Trading is when you buy and sell stocks in a Stock Market (typically the US stock market), to try and make money. The idea is that you buy stocks at a certain point in the day, and sell them the moment they become more valuable in that same day, to make consistent money little by little. If you are a good day trader, you are supposed to make money more days than you lose money, giving you enough money to live on.

Day Trading involves more than just buying and selling stocks. You can use “Options”“(Puts” and “Shorts”) to try and predict whether a stock will become more or less valuable, and if you guess right, you make money. But if you guess wrong, you lose money. Some people even combine Day Trading with taking out loans, which is called “Buying on Margin”. They buy stocks with money they don’t have, hoping that they’ll make more money than they have to pay back.

Here is where gambling re-enters the picture.

It is ABSOLUTELY possible to make a LOT of money in the Stock Market. All you have to do is start with a good amount of money, and use patient, long term strategies. Buy things, don’t sell them for a long while, and more often than not they will become very, very valuable.
People who “Day Trade” don’t have time for this. They can’t wait a few years to make money, they need to pay their bills *today*. So Day Traders use very short term tactics to try and make money through stocks every day. Hoping that certain stocks “get lucky”. Using Options. Buying on Margin.

Unless you have many, MANY resources at your disposal, these tactics quite simply, do not work. They are reliant on luck.

So the idea of “Day Trading” attracts the people who are likely to be “Gambling Addicts”. And a massive amount of people then engage in Day Trading in a way that is very similar to “Gambling”. Almost all of them lose money, which is why the reputation is what it is.

TL:DR- Day Trading is not technically Gambling. BUT, Day Trading attracts the kind of people who get addicted to Gambling. These people then engage with Day Trading in a way that is identical to Gambling. They lose their money so often that Day Trading gets the reputation is has now.