I doubt it that you won't affect you when a crash happens.
You're relying on the market, you've got holdings while you trade and if that happens, you'll be mostly affected by it and that's why everyone is affected during bear market.
Although the good thing with day traders, they can cope up with their daily trades but not with what they hold unless they DCA.
Agreed, however a crashing market while bad is not completely bad for traders, traders can make money as long as there is a strong trend, it does not matter the direction of the trend itself as long as it exists, however the problem is that after that the price has the tendency of not moving for a long time, just take a look of what happened after the crash of 2017 and the winter that came in which the market did not moved for years, and these are the market conditions that really destroy traders as there is no volatility to take advantage of.