Well, in the sense that just about everything isn't 99% certain, sure. But just letting your money sit in an account getting eaten alive by inflation is not really a great idea.
You have to make your money work for you, and it's definitely hard to do.
That I can agree with.
However, it's good to have a good amount of cash that is easily accessible just in case you need it quickly. If it's tied up in an investment, it's not always easy to pull it out quickly enough. Or there may be fees tied to those investments (selling fees or early-out penalty fees) that make them less attractive in the short term.