What do two billionaires chat about? If they're Steve Case and Dan Gilbert, they swap perspectives on lessons learned as entrepreneurs — to help early stage companies grow.

Gilbert, founder and chairman of Quicken Loans Inc. and Rock Ventures LLC, spoke at a two-day "Rise of the Rest Fund Summit" in Chicago last week. AOL co-founder Case interviewed him for an hour before an audience of nearly 100 founders of early-stage companies that have seed-capital investments from the fund that Case started, which has attracted investors like Gilbert and sports team owner and entrepreneur Ted Leonsis.

Case's idea was simple: Create a fund that invests in promising companies outside of Silicon Valley, New York and Boston, investing alongside local or regional funds, with no more than 10 to 20 percent of a given capital raise round.

The event gave Gilbert a chance to talk about his own entrepreneurial story and to tout Detroit as a place for startups and tech companies. "I'm getting calls, six to nine calls a month, from CEOs of Silicon Valley companies who have had it," Gilbert said. "They can't find people, they can't get people to stay, it's not affordable. Amazon and Bezos are the bellwether of what's happening (on the Coast)."

Gilbert also spoke to a business philosophy of engagement in the city as "doing well by doing good. … We call ourselves 'more-than-profit,'" offering the example of the yearlong project of using volunteers from his 13,000-strong downtown workforce to scan mountains of paper documents to give the Detroit Public Schools Community District its first digital records of high school diplomas that alumni could use for job search requirements. "What did that cost us?" Gilbert asked rhetorically. "That was an incredible motivator for our people, who felt like they had impacted our city."

The summit included one-to-one mentoring by fund investors and limited partners as well as networking and "big-stage" speakers.

Detroit-area companies in the portfolio include GuardHat, an Internet-of-Things maker of wearable technology and workplace safety software; Sahi Cosmetics, whose products focus on ethnic skin tones; StockX, the online platform for the buying and selling of consumer goods, especially sneakers, handbags and other limited-run items; and Waymark, a video marketing startup. Another company, Denver-based WTRMLN WTR, was co-founded by Detroit expat Jody Levy.