Here's my take on why it's so difficult to successfully day trade the markets:
1982 was the turning point for stocks traders, the face of trading was turned upside down.... no longer could traders determine the value of a stock based on its assets and profit potential then enter a trade in the right direction at a realistic price, but from 1982 it was the index that set the price of the stock rather than the stock price setting the index. Not long thereafter, algo trading targeted the indices, Index HFT was born, the index futures became so dominant that all short-term correlation between fundamentals and stock price were thrown out the window. In fact, many traders of the index don't even realize that say, a 5% drop in the index results in a 5% drop in the individual stock price (sometimes more if the index is weighted) of all the components of the index, regardless the quality of the stock... the index now drives the stock price, not the other way round.
The holy grail in short term trading is no longer in the ability to accurately determining the fundamentals but rather it is in proper risk management. Bots can manipulate markets and reverse a trend for no reason at all, to have a position in the right direction is luck of the draw, losses are inevitable and so only good risk management can make the difference between success and failure as a day trader.
But not all is lost... ultimately, the fundamentals still count, markets will always gravitate towards the fundamentals... it might take weeks or even months but eventually, the fundamentals will adjust stock prices to fair value. Trading on a longer horizon and in tune with the fundamentals still works and IMO is still far more profitable than day trading. 100 years of history of the US markets tell you that the indices will always go higher given enough time, why? because components making up the index is dynamic, failing companies are removed and replaced by new performers. Staying long in the index will always profit you, trading the indices on fundamentals i.e. buying at the oversold point and taking profits at overbought points will not only consistently give profits but will also beat the index's natutal gains.
I wish you good luck on whatever method you chose to trade and if you are day trading, do exircise proper risk management, it is even more important than choosing the optimum entry price.