Kahr grew up in New York City, where he attended the Fieldston School of the Ethical Culture Society.
[2] In 1981 Kahr partnered with the Parker Pen Company to create First Deposit Corp., a non-bank bank that issued credit cards targeting the subprime cardholder market.
First Deposit, later acquired by Providian Financial, used Kahr's research to identify the most profitable subprime customers — those who paid interest on revolving balances — and then offered them enticements such as zero percent introductory rates, cashback reward programs and 2 percent minimum payments,[2][4] pairing these with severe penalties for late payments or credit limit violations.
After rapid growth through the 1990s, Providian reported large losses and faced a class action lawsuit over its marketing and disclosure practices.
In a series of memos that were revealed in the lawsuit, Kahr urged the company to "squeeze customers" and to avoid disclosing card expenses.