It’s not entirely without risk. 2008 saw the S&P lose over 30% for the year, and 2002 was over 20%. But it is up more often than down year-to-year, and it is usually up by at least 10%.
I found some good charts here, even though it is a EU site:
https://curvo.eu/backtest/en/market-index/sp-500?currency=usd
If you are investing for the long haul , you will take the occasional 30% haircut if you can get 10-20% the rest of the time. But it would suck if you got that 30% haircut just before you needed to sell…
Most dad jokes here are old and stale, it’s good to have one that’s current.