If you read to the end of the article, they mention that Kodak had a fully working DSLR in 1989, similar to todays DSLRs. So they did the right thing in 1975 by

If you read to the end of the article, they mention that Kodak had a fully working DSLR in 1989, similar to todays DSLRs. So they did the right thing in 1975 by working on a digital camera, but they did the wrong thing in the 90ies by not selling it once they had it.