Two friends started a greeting card company on the internet. It was cheap to launch and it instantly reached millions. Then one day without warning, Facebook changed the way it did business.

This is a story about survival in the age of Facebook, when a privately held algorithm can turn a beloved product into a hobby with no monetary value. Subplots include forays into alcohol, cheap laughs, and low-paid freelancers.

Duncan Mitchell was a creative director at an ad agency in 2005 when his friend Brook Lundy, who worked at another agency, approached him with the idea to create online greeting cards. The ones available at the time seemed staid or unfunny. More salient, an e-card company, Blue Mountain, had recently been bought for stock and cash worth up to $1 billion.

“In the back of your head, especially back then, you’re like, Is this the next million dollar idea?” Mr. Mitchell, 48, said.