True Teva did not invent the drug. They started funding it after Bornstein's initial US trial in the 1980's (using frozen drug supplied by the Weizmann Institute). But Teva did the heavy lifting in the decade thereafter, including the large multi-center trial using a non-frozen version and all the manufacturing and stability issues related to a one-of-a-kind drug. So what they did there is certainly a much greater commitment than for a generic enox.
Obviously Teva's focus has not been branded drugs. But that does now seem to be changing to a degree.