The first ballpoint pen was sold in 1945 and cost $180 in today's dollars. As the price dropped, it quickly replaced the messy, finicky fountain pen. The BBC has a great article about the invention and rise of the ballpoint as the ultimate writing implement.
"What the ballpoint pen did was to make writing something that could happen anywhere. I've written in snow and rain, on the back of an ATV and in a boat at sea and in the middle of the night," says Sax. Biros don't drain batteries, they don't require plugging in in the middle of nowhere, and even the tightest pocket can accommodate them. "It only fails if it runs out of ink," Sax adds.
The ballpoint pen is testament, Sax says, to one of the tenets of "really great design – it almost disappears. If the ballpoint didn't exist and you launched one today on Kickstarter, it would be the biggest thing ever," he says.