Analysts say John G. Sperling helped establish a large niche in higher education by offering classes to adults at times and places that fit their schedules. (AP)

John G. Sperling, a former history professor who founded the for-profit University of Phoenix and oversaw its growth into a colossal higher education business central to debates over student debt and government regulation, died Aug. 22 at a hospital in Marin County, Calif. He was 93.

The cause was sepsis, said Jorge Klor de Alva, a former Phoenix president.

Dr. Sperling, a pioneering and polarizing figure in higher education, saw nothing wrong with turning a profit through the instruction of working adults who relied heavily on federal grants and loans to pay tuition.

Many of those students say Phoenix degrees have helped their careers, but many others have defaulted on debt after leaving school. The Obama administration, citing high student loan default rates across the for-profit sector, has sought tighter oversight of the industry. The latest government data show about a quarter of former Phoenix students default on federal student loans.

To criticism of his business model, Dr. Sperling replied: “Why do people say such things about us? Fear! Fear! Fear! They’re scared to death of us.”

He pushed back hard against regulators and others who sought to hem in his business, forging ties with lawmakers through extensive lobbying and political donations.

In the past two years, he gave more than $50,000 to the Democratic Congressional Campaign Committee and $2,500 to Rep. John Kline (R-Minn.), chairman of a committee that oversees education.

Some Democrats resisted Dr. Sperling’s arguments against what he viewed as excessive government regulation of for-profit schools.

“To have someone saddled with a debt they can’t pay back, and they don’t finish school, and put their financial lives in jeopardy, that’s a double-edged sword,” Rep. Raúl M. Grijalva (D-Ariz.) told Bloomberg News in 2010. “The community colleges are there, that’s accessible and inexpensive.”

Raised in poverty during the Depression, Dr. Sperling became a billionaire through the company he founded in 1973 that is now known as Apollo Education Group. Forbes listed him in 2006 among the 400 richest Americans, with a net worth of $1.3 billion.

The company’s flagship school, launched in 1976, eventually became the largest higher education institution in the nation. The University of Phoenix’s online operation reported 212,000 students in fall 2013, according to federal data, with thousands more enrolled at branch campuses across the country. The largest public university, Arizona State, and the largest private, nonprofit university, Liberty, each had nearly 80,000 enrolled.

Enrollment at Phoenix and other for-profit schools has shrunk significantly in recent years amid economic and demographic flux and increased government scrutiny of the industry.

Still, analysts say Dr. Sperling helped establish a large niche in higher ed by offering classes to adults at times and places that fit their schedules. The Phoenix brand is widely known online and through sites in office parks and other utilitarian locations that evoke nothing of the traditional college campus.

“Here’s a guy who imagined a form of education that became a national model,” said Arthur Levine, a former president of Teachers College at Columbia University who heads the Woodrow Wilson National Fellowship Foundation in Princeton, N.J. “He imagined adult education — programs for adults that would be delivered online and through regional centers. At the time he imagined it, it was brand new, and it was radical.”

Born Jan. 9, 1921, in rural Nodaway County, Mo., John Glen Sperling was youngest of six children in his family of sharecroppers. By his own account he was poorly educated, sickly and dyslexic. After his father’s death, the family resettled in Oregon.

Following high school graduation, he joined the Merchant Marine in the late 1930s.

“In those days very intelligent men were sailing because there were very few opportunities at the end of the Depression,” he told an interviewer. “I met some really wonderful shipmates and they got me interested in literature. Once I learned how to read, then I got interested in education.”

He served in the Army Air Forces during World War II and, on the GI Bill, graduated in 1948 from Reed College in Portland, Ore. He received a master’s degree in history from the University of California at Berkeley in 1951 and a doctorate in economic history in 1955 from the University of Cambridge in England.

In 1960, Dr. Sperling began teaching at San Jose State University, where he was a union organizer and became involved in remedial education for incoming freshmen.

He also took a liking to training — and then teaching — the teachers and police officers who worked with troubled teenagers. That gave him the idea of offering degree programs for adults. By his early 50s, he had launched an education company, moving to Arizona after facing problems with California regulators. He took the company public in 1994 and made a fortune as online enrollment boomed.

He relished what he had accomplished as a former tenured professor who built a business that enabled working adults to earn a diploma in the time it took full-time students to do so on a traditional campus. “Because this challenged many of the sacred tenets of academe, it was met with hostility bordering on rage,” Dr. Sperling wrote in a 2000 memoir, “Rebel With a Cause.”

Dr. Sperling had homes in Phoenix, San Francisco and Marin County, according to Klor de Alva. His marriages to Barbara Sperling and Virginia Sperling ended in divorce. Survivors include a companion, Joan Hawthorne; a son from his second marriage, Peter V. Sperling, who is chairman of Apollo Education Group; and two grandchildren.

Dr. Sperling was known for his advocacy of legalizing marijuana and for funding clones of his pet dog, Missy, a border collie-Siberian husky mix. A profile of Dr. Sperling in the Chronicle of Higher Education includes a picture of him with Missy 2.

“They say I’m eccentric,” he told the Chronicle. “I don’t feel eccentric. I’m indifferent to my reputation. I’ve never lost one minute of sleep over it.”