Hi, Alexa, It’s Jeff Bezos. How should I spend my time now?

If history is any guide, the next act of Jeff Bezos, the man who turned a crazy-at-the-time idea to sell books over the internet into a $1.67 trillion behemoth, could be more consequential than the last.

Mr. Bezos announced last week that he will step down as chief executive of Amazon, though he will continue to have a great deal of control over the direction of the company as its executive chairman and largest shareholder. His move will enable him to spend more time on other interests and find ways to spend a personal fortune that, thanks to Amazon’s booming stock price, is now about $195 billion.