Entrepreneur Garrett Campbell has a 6-mg “cool mint” Zyn tucked under his lip at all times during his mammoth 15-hour workdays, aside from when he is eating. “I was always very against nicotine,” says the software company founder. The 26-year-old saw his peers using nicotine pouches at college, when they first emerged as a potential productivity-boosting hack, and considered it a “degenerate thing to do.” But then all of his fellow founders started fueling themselves with nicotine pouches, of which the Philip Morris International–owned Zyn is the market leader. The company distributed 794 million cans in the US in the last financial year, a 37 percent increase over the previous year. Now, Campbell says “every single one” of his friends that runs a company does so with a nicotine pouch in their mouth.…