[3] He later returned to Princeton to study architecture and participated in a prehistoric excavation in Greece as a field architect.
[3] After completing an MBA from Harvard Business School, Cotsen joined Natone, a cosmetics supply company founded by his father-in-law, Emanuel Stolaroff.
[3][2] After his retirement, Cotsen dedicated his time to collecting contemporary textile fragments, Japanese ceramics, and turned wood.
[3] At the time of his death on May 8, 2017, in Beverly Hills, California, Cotsen had donated approximately half of his collection to institutions such as the Asian Art Museum in San Francisco, Princeton University, and the Museum of International Folk Art.
[3][2][5] He was a major donor of the University of California, Los Angeles's Cotsen Institute of Archaeology, which was renamed in his honor in 1999.