What facts from the article show that Whitman couldn't be a full-time poet?

This question is incomplete, here´s the complete question.  

“O Captain! My Captain!” by Walt Whitman. Author Biography and Historical Context

Walt Whitman was born in 1819 in Long Island, New York and grew up in New York  City. He left school at eleven and began working to help support his family. Even  after he had left school, he was an avid reader and self-taught. He worked for a  newspaper, learning about the printing world and he also worked as a teacher for a  short period of time.

In 1855 he published the first edition of Leaves of Grass, a collection of poems.  Whitman published the first edition himself – fewer than 800 copies. The book  wasn‘t favorably accepted by the few who read it, but a copy of the book was sent to  Ralph Waldo Emerson, a well-respected poet and lecturer of the time. Emerson  wrote a glowing letter about the value of the book. Emerson‘s words of praise were  later reprinted on the cover of future editions of Leaves of Grass.

Even with Emerson‘s praise, the general public was not quick to accept Whitman‘s  poetry. The writing style of Leaves of Grass was not like other poetry of the time,  and the subject matter was somewhat controversial and difficult for the average  reader to understand. As you know, Henry Wadsworth Longfellow was a popular  poet of this time period, and his poems were written with regular rhythms and  distinct rhyme patterns. But  Whitman‘s poems sounded different, and were  therefore largely dismissed or criticized. Read the first lines of Leaves of Grass:

I celebrate myself,

And what I assume you shall assume,

For every atom belonging to me as good belongs to you.

I loafe and invite my soul,

I lean and loafe at my ease … observing a spear of summer grass.

In spite of the lack of public support, Whitman continued to write poetry. To support himself and his family, he continued to work in the newspaper business.  When the Civil War began, his younger brother joined the army. After learning that  his brother may have been injured in battle, Whitman traveled to the South to find  him. His brother had only suffered minor injuries, but through his travels, Whitman  observed the results of the battle injuries the soldiers endured. Seeing the wounded  and dying soldiers had a great impact on Whitman. He decided to move to  Washington, D.C. where he helped in an Army hospital.

In 1865, Abraham Lincoln was assassinated. Whitman was a great admirer of  Lincoln and had even seen him on the streets of Washington. His death upset  Whitman greatly and, like many writers who struggle with emotions, he turned to  writing and poetry. Whitman published a book of poems about the Civil War  entitled Drum-Taps that included two poems about Lincoln‘s death: ―When Lilacs  Last in the Dooryard Bloom‘d‖ and ―O Captain! My Captain!‖

Whitman continued to live in Washington, on and off,  until 1873 when he suffered from a stroke. He then  returned to New Jersey to live with family. Whitman  received numerous visitors, many of whom were  famous writers of the time, and he continued to write.

Sadly, his only poem that was widely accepted and  reprinted in his lifetime was ―O Captain! My Captain! This poem is written in a more conventional style with  rhythm and rhyme that readers were familiar with.  Additionally, the subject matter struck a chord with  readers who could understand the conflicting emotions  of the poem.

Walt Whitman‘s poems helped shape America‘s identity; he loved writing about the  common worker and American life. But, his poetry remained controversial throughout his life. Some critics loved it, and some hated it. Regardless, Whitman‘s  poetry changed the way poems were written. Today, he is considered the father of  free verse poetry. Since Whitman‘s death in 1892, Leaves of Grass has been  translated into many languages and is prized as an important piece of American  Literature.

Whitman´s lack of resources to be able to be a full-time writer can be first noticed on the facts presented about his background, having left school at a young age to work so he could help support his family.

His lack of resources is also shown by him having to publish the first edition of Leaves of Grass by himself, with a limited number of copies as a result.

Finally, the article shows that Whitman couldn´t be a full-time writer, as he had to work in the newspaper business so he could support his own family, and even ended up working in an Army hospital during the Civil War.