I've been in the markets over 25 years and have done really well by any estimation.
I have dabbled in day trading a little bit, but it is more likely swing trades if you know what that means, Of these, i might hold for less than a day, maybe a little more depending what it is.
One important fact - i would never short term trade with more than half a percent of my overall trading portfolio. That means less than a penny on every dollar.
I have done thousands of these trades.
I have found that it goes in phases. Originally in the internet early days, I would almost always lose on the shortest term trading but win big on the buy and hold trades.
There was a phase about ten years ago when i counted about 90% of my trades were profitable.
Lately, just about none of them are profitable, but i only lose a few dollars when i lose because i cut my losses quick.
I think there are algos now that make it really tough.
That said, i am killing it on my long term buy and hold portfolio, and that allows me to play around with the short term trading, and that is all it is. In one respect, short term swing trades just keep me interested, but they don't amount to much either way. If it weren't for my need to watch the big stuff, I would feel that the constant attention necessary for short term trading would not be worth the time demanded to do it.
As far as the OP doing it for real, I'd say good luck to you. It really really is not something i would want to depend on, and I think there's a lot better ways to make a living.