Rich Hickey[0], in addition to making open source software[1], also produces closed source software[2]. Similarly, Joel Spolsky[3] is involved in a fairly high

Rich Hickey[0], in addition to making open source software[1], also produces closed source software[2]. Similarly, Joel Spolsky[3] is involved in a fairly high profile[4] closed source project. That's just off the top of my head. [0] https://github.com/richhickey https://github.com/richhickey [1] http://clojure.org http://clojure.org [2] http://www.datomic.com http://www.datomic.com [3] http://www.joelonsoftware.com http://www.joelonsoftware.com [4] http://stackoverflow.com http://stackoverflow.com