New traders are always opening and closing trades due to inexperience and their belief that there are unlimited profit opportunities whenever the market is open. Professional traders limit their trading activities because they know from experience that taking only higher probability trades sparingly produces the best results.
To understand why over trading is counterproductive think about it. You are handing over more fees to your broker and you are spending more time managing your open positions. You want less stress, less screen time, and less emotions when trading. You want more profit, more efficiency, and more enjoyment (freedom).
If you take 10 trades and your probability of success based upon random luck is 50/50 you end up with 5 winners and 5 losers. When you add in fees and psychological mistakes such as closing winners early and letting losers run you end up with a draw down in your account. Rather than trading randomly, what if you use a trading plan, trading rules, and you patiently wait for the high probability trades using confluence and If/Then scenarios? If you can add a winner or two and filter out a loser or two you should end up with a net profitable run for your 10 trades. If you wash, rinse, and repeat you can become a net profitable trader.