Although the beer was Koch's version of his great-great-grandfather's recipe, even his brewmaster father thought the idea of competing in a market with companies like Budweiser and Heineken was destined to fail.

But through extensive distributor outreach and marketing, Koch's company helped Americans embrace craft beer. Today the Boston Beer Company produces an estimated 1% of the beer in the US, and it had a record year in 2014, bringing in $903 million in revenue.

Koch has also run the Brewing the American Dream initiative since 2008. The program offers entrepreneurs in the food and beverage and hospitality industries free business coaching sessions and the opportunity to apply for loans.

He says that he most frequently reminds entrepreneurs to "pursue something you love."

"A small business is going to be very demanding of your time, your energy — it just eats your life," Koch tells Business Insider. "And if you're doing something you love, then you will accept and even enjoy that. If you're just doing it to get rich, you're gonna lose heart."