Yes scalping is risky:
To maximize few ticks, trading a larger size is essential: This is not forgiving.
I "give" +15% of my gross profits to my brokers.
Only 20% of my trades are limit orders, all others are market orders: I scalp the NQ future and I estimate that the slippage eats more than 15% of my gross profits.
Markets change all the time: To be able to adapt, discretionary is required.
The emotional impact is important (at least to me).
So, the odds are incredibly against scalpers.
No scalping is not risky:
Liquidity is your friend.
Don't fear or compete with HFTs, they actually amplify patterns (I am not talking about head and shoulders..)
I am in control and I always use a (large) stop, just in case: This stop is arbitrary at 1/2 of my daily loss limit and it is almost never touched.
Being in the market for few seconds or minutes removes all kind of black swan event.
No overnight positions, at least regarding my scalping activity.
My maximum daily net loss is not negotiable.