Koplar linked together and managed the Chase Park Plaza Hotel in St. Louis, Missouri.
In 1959, he launched the television station KPLR-TV (the call letters came from his last name) in a converted apartment building near the hotel.
He established a development at Lake of the Ozarks in 1964 that includes the Lodge of Four Seasons hotel, two golf courses, a marina, and Spa Shiki.
In 1966 he was listed as part-owner of the troubled midtown landmark Continental Life Building, along with St. Louis mayor Alfonso J. Cervantes and nationally known defense attorney Morris Shenker, who was also Koplar's brother-in-law.
Funeral services were held at Temple Emanuel in St. Louis and he was interred in the Koplar family mausoleum at New Mount Sinai Cemetery, Affton, Missouri.