Did an owner ever coach his own team?
Yes, George Halas of the Chicago Bears. He was a partial owner
of the team from 1920-1932 and sole owner from then until 1983 when
he passed away. He was head coach of the Bears for 40 years in four
10 years intervals (1920-1929, 1933-1942, 1946-1955,
1958-1967).
Halas also played end for the Bears between 1920-1928 so, during
that time, he was player, head coach, and owner.