Why buy a cow when milk is (so) cheap?

Why buy a cow when milk is (so) cheap?

1. Proverb If someone is already able to obtain some commodity or benefit freely or easily, then they won't be inclined to pay for the source of it. The ability to read the news is free from countless websites on the Internet has dealt a huge blow to the newspaper industry. After all, why buy a cow when milk is so cheap?
2. Proverb If a man is already having sexual intercourse with his partner, then he won't be inclined to commit to marriage. There are myriad reasons why I don't want to get married, but my girlfriend thinks my stance boils down to "Why buy a cow when milk is cheap?"
See also: buy, cow, milk, why