How did Margaret Brown get the nickname "Unsinkable Molly Brown"?

Margaret Molly Brown

When the Carpathia arrived at New York's Pier 54, over 30,000 people, including reporters, clamored to interview the Titanic survivors. When reporters asked Margaret Brown to what she attributed her survival, Margaret replied, "Typical Brown luck
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We're unsinkable." Reporters began referring to her as the "Unsinkable Mrs. Brown".  The nickname of "Molly" was a Hollywood invention created years later in the 1930s. It was part of a highly fictional tale that became the basis for the 1960 Broadway musical, The Unsinkable Molly Brown. In the movie Titanic, we get a glimpse of the friendship between Margaret Brown and John Jacob Astor.

Before boarding the ship, Margaret had been traveling with J.J. Astor and his wife Madeline in Cairo, Egypt. Margaret booked a First Class passage on the Titanic after learning that her grandson Lawrence was ill.