Answer by taking a quote from the following article:

John F. Maulbetsch (June 20, 1890 - September 14, 1950) was an All-American football halfback at Adrian College in 1911 and for the University of Michigan Wolverines from 1914 to 1916. He is also a member of the College Football Hall of Fame. After playing with an independent football team in Ann Arbor and at Adrian College, Maulbetsch became one of the most famous American football players in 1914 while playing for the University of Michigan. Maulbetsch became known as the "Human Bullet" because of his unusual low, line-plunging style of play, and was also known as the "Featherweight Fullback" because of his light weight and small size.

In January 1921, Maulbetsch was hired as the head coach at Oklahoma Agricultural and Mechanical College (now Oklahoma State) in Stillwater, Oklahoma. He served as the coach at Oklahoma A&M from 1921 to 1928, where his teams posted a 28-37-6 (.437) record. In 1924, his team went 6-1-2 and shut out Oklahoma (6-0), Arkansas (20-0) and Kansas (3-0). Maulbetsch's Aggies also shut out Phillips that year, 13-0. After the season, attempts were made to lure him to Washington University in St. Louis, Missouri, but Maulbetsch said he was satisfied with his position in Stillwater.  Maulbetsch arranged a game in Ann Arbor against his alma mater to start the 1926 season. Michigan beat the Aggies, 42-3. Despite an overall record of 3-4-1, Oklahoma A&M won its first conference football championship by going 3-0-1 in games against Missouri Valley Intercollegiate Athletic Association opponents. Maulbetsch also drew attention in 1926 for his disciplinary methods. When the team lost two games due to fumbles, he ordered eight of his backfield players to carry footballs with them to classes throughout the week and instructed other team members to try knocking the balls from under their arms. The penalty for losing a ball was "a hard run around the stadium." He also ordered one of his ends to wear boxing gloves after he poked an opposing player in the eye.  The Aggies won only one game against seven defeats in 1928. In late November, the day after a 46-0 loss to Oklahoma, newspapers reported that "reliable sources" had said Maulbetsch intended to resign. Maulbetsch immediately denied the rumor, saying: "I have not resigned. I am aware that a faction here is trying to get me out, but I do not intend to throw up the sponge." In December, pressure to fire Maulbetsch grew, and one Oklahoma newspaper observed: "Coach Maulbetsch of the A. & M. football team is the object of attacks from many sides because of the rather poor showing made by his team during the past season. They are looking for a goat and just now Johnnie is cast in that role. Regardless of his past record, those who demand victory at any price and by any means whatsoever, are insisting that he be fired forthwith and a man be placed in the position who, by fair means or foul, will gather in a team that will win victories and never lose a game." Ultimately, Maulbetsch resigned at the end of May 1929 as Oklahoma A&M's coach in football, baseball, and basketball. It was announced that he would spend the remaining year of his contract on a leave of absence at half pay.

What made him decide to coach?