Although I agree to some point, keeping too much in ETF increases the risk of it all going down the exact moment you need it since you loose the job at the same time the market crashes in a crisis.
You forget that I have a buffer of 3 months plus I live in Europe, so the money I will receive for unemployment would help me to further extend my financial cushion. I can create a standing order with a limit and only sell some ETFs if the price is reached, in order to reduce the financial losses.
Plus if I invest my money in ETFs long enough I would most certainly always be on the plus side.