Utilize your financial knowledge, give your answer or opinion to the input question or subject . Answer format is not limited.

Is it a good idea to put everything in the S&P500?
What you choose to invest in depends largely on your own goals and time horizon.  You state that your time horizon is a few decades. Most studies have shown that the equity market as a whole has outperformed most other asset types (except perhaps property in some cases) over the long term.  The reason that time horizon is important is that equities are quite volatile. Who knows whether your value will halve in the next year? But we hope that over the longer term, things come out in the wash, and tomorrow's market crash will recover, etc.  However, you must realize that if your goals change, and you suddenly need your money after 2 years, it might be worth less in two years than you expect.