Before 2001, the year that Hardly Strictly Bluegrass festival debuted to a crowd of perhaps 13,000, the then-67-year-old investment banker Warren Hellman was a music industry novice, having neither seriously played an instrument nor booked a concert.

Eleven years later, the billionaire declared the annual hoedown, bankrolled by him and free to the public, to be his greatest legacy.

But just as notable as the festival itself is the musical education of its founder who took up the banjo in earnest after his 70th birthday. While his peers were hitting golfballs, his final decade – Hellman died Sunday night at 77 -- was filled with sound checks, jam sessions and earlier this year, a seat on the band tour bus with his band the Wronglers. 

His commitment to his favorite genres, bluegrass and old time, the songs of the proletariet, was total. In the past few months, when his illness would force him into a semi-conscious state for short spells, his bandmates noticed that his hands would reflexively stroke an imaginary banjo, sometimes for hours. On Tuesday, in between trips to the hospital, he called for the Wrongler's last practice, performing through extreme pain.

“He still continued his business and philanthropy but music became his life,” said Dawn Holliday, the booker for Hardly Strictly Bluegrass.

The annual festival has become known nationally for its eclectic mix of American roots music drawing bold-faced names from every musical quarter. Performers such as Elvis Costello, MC Hammer, Conor Oberst and Broken Social Scene have played alongside acoustic icons Emmylou Harris, Merle Haggard, Gillian Welch, Allison Krauss and others. Audience members have grown to expect the unexpected —country music’s Ricky Skaggs jamming with Bruce Hornsby or T Bone Burnett hanging out onstage with John Mellencamp.

It’s now one of the biggest music festivals in the United States, This past fall, over 600,000 people showed up in a part of Golden Gate Park that was recently rechristened “Hellman’s Hollow” by San Francisco supervisors. 

Family members say that Hellman has endowed the festival for 15 years after his death.  "I know that next year we will have one fuck of a festival," said Holliday.

“Every musician I know wants to play this one festival,” Rosanne Cash wrote in an email.

“Half the musicians I know, this is their favorite,” said country icon Jimmie Dale Gilmore, who has played at all but one Hardly Strictly. “It’s certainly mine.”

“I don’t think there’s another festival like this in the world,” Emmylou Harris said in 2005.

Hardly Strictly Bluegrass began as no more than idle conversations.

On a ski trip in 2000, Hellman mentioned his fantasy about starting a bluegrass festival to his friend Jonathan Nelson, the founder of Organics, Inc. and a former employee at Bill Graham Presents. Nelson encouraged him “‘to just do it’,” Hellman said in a video interview. Nelson then introduced Hellman to Dawn Holliday, an experienced music booker who works for Slim’s and Great American Music Hall and Sheri Sternberg, an event producer, over lunch.

“That lunch was the first time the four of us met,” Holliday said. “Warren said that he always wanted to have a bluegrass festival in the park and I said, we can do that.”

But Holliday also warned that if the festival only had music that Hellman knew and loved —namely, Hazel Dickens, a bluegrass performer known for her powerful political songs dealing with coal mining strikes in the late ‘70s and early ‘80s -- “there will be about 13 people there.”

Hellman had no problem letting Holliday and others broaden his tastes through hours of back-and-forth on contemporary and older music. Her vision for an American roots festival included famous acts like Emmylou Harris alongside up-and-coming acts like the Old Crow Medicine show.

“I gotta tell you, it was beyond fun doing it with him,” she said, “His interest was growing and growing.”

It’s common lore that Hellman almost failed to convince Dickens to perform at the first festival. As Ron Thomason, a musician in the bluegrass band Dry Branch Fire Squad and has known Hellman for years through horseback riding competitions as well as Hardly Strictly, remembered it, the working class Dickens was “quite conflicted” about whether to accept Hellman’s offer to play the fledgling festival.

“I happened to be out in [Washington] DC where she lived at the time. She told me, ‘I met this man, you won’t believe it, he’s really rich. ‘I said, ‘that’s not the kind of company you usually mix with,’” said Thomason.

But Dickens, who died this past year, told Thomason that Hellman said he wouldn’t do the festival without her. Not only did she agree to perform the first year but she appeared every year after that until her death in April 2011.

“Hazel always had the top spot,” Thomason said, “Warren was always dedicated to putting her out front. Robert Plant, Elvis Costello, sometimes they’d be on a subordinate stage.”

 In her absence, Hellman dedicated this September’s event to her.

The festival grew rapidly after the first year, which was a one-day event with just nine acts besides Dickens, including Allison Krauss and Emmylou Harris. This past year, over 90 musical acts performed on six stages over four days.

Gavin Newsom, the former mayor of San Francisco, noted in 2010 that a crowd roughly the equivalent to the population of the city now shows up every year.

According to Holliday, the festival expanded in part because Hellman refused to say no to any artists, even when Holliday recommended they not be asked back to make room for new performers. “I told him we can’t have the same concert every year or no one will come,” she said, laughing.

Among musicians, word of mouth continued to spread that a crazy billionaire was putting on one of the best-run festivals in the country.

Hellman lavished attention on everyone from the groundskeepers to the superstars, giving the entire team watches in 2005 to celebrate Hardly Strictly’s 5th anniversary.

Every year a private party is held at Slim’s exclusively for the musicians and crew to meet and hang out with each other. Traditions developed, such as Emmylou Harris closing the show every year and Thomason’s band giving an annual lavish introduction to Hellman.