In the UK normal employees are automatically enrolled to invest in their pension (life savings for retirement) and this will be at least partly in the stock market. It is normal and sensible.
In fact I wouldn't be surprised if you could lose your financial advisor's license for suggesting everyone keep their life savings as cash - it's such bad financial advice.
If you keep your life savings as cash you are optimising for the 99th percentile of bad outcomes for the global economy, and losing out massively in every other likelihood.
>it could even be $0.00
It is unlikely that the value of the S&P500 will be zero in our lifetimes. If it is, your 50,000 US dollars won't be worth much.