On the brink of 40, Gev Danielian could have gotten a Porsche; he could have gambled or had too much to drink. Instead, in June 2021, he planned a prudent celebration at his home in Los Angeles and allowed himself one mild regression. He blanketed his lawn in several hundred balloons.

Dozens and dozens of balloons in a of matte neutrals; several accent balloons streaked to mimic Carrara marble. At first, Mr. Danielian had been skeptical when his event planner, Edgar Hay, proposed them. “I was hesitant — I’m not a child,” he said.