While we'd love to say that every indie author immediately becomes a bestseller, can quit their day job, and write full time, the truth is not so simple.
Many indie authors will achieve modest success. Some will not be successful. Most have the potential for success but not the wherewithal to invest properly in accomplishing it to any degree.
Success comes in part from luck, but in a greater degree from effort. There are numerous examples from the print world of authors who did not succeed with their first, second, or even third attempts.
Stephen King's first book, Carrie, was rejected THIRTY TIMES before finally being published. He actually threw it away and his wife dug it out of the trash and rescued it. Rudyard Kipling (author of The Jungle Book, winner of the Nobel Prize for Literature) was "fired as his role as contributor to the San Francisco Examiner in 1889 because he was told by an editor, 'I’m sorry Mr. Kipling, but you just don’t know how to use the English language.'" [Thought Catalog].
What finally made them successful? As much as anything else, it was their own tenacity.
They didn't give up.
So keep writing - even when it seems impossible, even when it seems pointless.
Keep writing.