Growing up in a middle-class family in New Jersey, the son of a stockbroker father and a legal mediator mother, he had a motley assortment of jobs in high school, from working at a thrift shop to selling tie-dyed shirts on New Jersey trains on his way to some of the 80 Grateful Dead concerts he attended. Although he wasn’t a coder, he liked hanging around Radio Shack and taking apart radios and TVs... Later he worked in sales at research companies like Gartner, eventually founding a payments startup in 2004 that allowed people to pay rent electronically. Gardner was so short on cash over the next few years that he sometimes put mortgage payments on his credit card. In 2007 he sold the company to MoneyGram for $28 million and stayed on as an executive for two years.

https://www.forbes.com/sites/jeffkauflin/2019/03/26/it-took-three-tries-but-this-entrepreneur-transformed-his-struggling-startup-into-a-2b-unicorn/amp/