It's not risky, IF you sell high and buy low.
Unless you buy low and the market keeps going lower, as has happened to my brother on occasion.
You can't say that buy and hold works.
No, but Warren Buffet can. Have you ever read anything by Soros, the guy who bet against the pound and won?
He was a seriously mathematical guy who did significant risk modeling to backup his trading. His stuff is not easy to follow.
You may well end up being good at day trading, but short term moves are driven by market emotion and are not reliable so you are engaging in a fairly high risk activity. Hopefully you are aware of the risks and are taking steps to manage them.