Most day traders over-trade and cant beat commissions, spread and slippage etc. If you make just 4 trades a day that is 1000 trades per year. Most of those trades will be low quality trades. The costs incurred taking around 1000 low quality trades become a very high overhead to beat. And over 2 or 3 years even higher. Not to mention the psychological stress of being a day trader and getting beaten up by the market on a regular basis.
If that is your experience you are absolutely right to never daytrade. You should be better to survive daytrading.
secret : when there is signal, blindly pull the trigger without 2nd thought, without hestitation, without delay.
I am far from superman and probably less smart then the average ET member (in most areas, but apparently not in daytrading). You need to know what you need to know. Not needed to be a Phd or a math wizard.