[stefanheule]

Personally, I'm the former kind of person. I have enough to not suffer from a 40% downturn, and I'd rather have my emergency fund invested in the market.

But I agree, not everyone is like this. Note though that you don't have to invest in the S&P500, there are many lower-risk (and lower-return) investments to choose from. For instance, bonds historically have seen 6% average return, with their worst year seeing a drop of 8.1% (source: https://investor.vanguard.com/investing/how-to-invest/model-...).