It needs sheer dedication, hard work, patience, quick wit and immense knowledge to be successful in intraday trading. Successful intraday trading involves 90% waiting and 10% execution. So, yes, it can make a trader rich in a relatively short period of time if the correct processes are followed, and yes, it is possible to hold on to the profits in the long-term if the correct strategies are followed.
Originally, the most important U.S. stocks were traded on the New York Stock Exchange. A trader would contact a stockbroker, who would relay the order to a specialist on the floor of the NYSE. These specialists would each make markets in only a handful of stocks. The specialist would match the purchaser with another broker's seller; write up physical tickets that, once processed, would effectively transfer the stock; and relay the information back to both brokers. Before 1975, brokerage commissions were fixed at 1% of the amount of the trade, i.e. to purchase $10,000 worth of stock cost the buyer $100 in commissions and same 1% to sell. Meaning that to profit trades had to make over 2 % to make any real gain.
The price movements of any stock are posted throughout the trading day and summarized at the end of the trading day. For example, April 2, 2019, shares of Apple Inc. (AAPL) opened at $191.09 and closed at $194.02. During the day, as indicated in the "day's range" listed to the right of the closing price, shares dropped as low as $191.05—the intraday low—and hit a peak of $194.46—the intraday high.

Day trading was once an activity that was exclusive to financial firms and professional speculators. Many day traders are bank or investment firm employees working as specialists in equity investment and fund management. Day trading gained popularity after the deregulation of commissions in the United States in 1975, the advent of electronic trading platforms in the 1990s, and with the stock price volatility during the dot-com bubble.[2]
By holding overnight, the swing trader incurs the unpredictability of overnight risk such as gaps up or down against the position. By taking on the overnight risk, swing trades are usually done with a smaller position size compared to day trading (assuming the two traders have similarly sized accounts). Day traders typically utilize larger position sizes and may use day trading margin of 25%.
Spread trading This high-speed technique tries to profit on temporary changes in sentiment, exploiting the difference in the bid-ask price for a stock, also called a spread. For example, if a buyer’s bid price drops suddenly, the day trader might step in to buy and then try to quickly resell at the stock’s ask price or higher, earning a small “spread” on the transaction.
Assess how much capital you're willing to risk on each trade. Many successful day traders risk less than 1% to 2% of their account per trade. If you have a $40,000 trading account and are willing to risk 0.5% of your capital on each trade, your maximum loss per trade is $200 (0.005 x $40,000). Set aside a surplus amount of funds you can trade with and you're prepared to lose. Remember, it may or may not happen.