Why did Franz Schubert work as a schoolteacher?

Franz Schubert worked as a schoolteacher primarily to secure a livelihood, as he was not yet able to support himself solely through his compositions. After leaving his studies at the Stadtkonvikt in 1812, he attended a teachers' training college in Vienna and subsequently became an assistant in his father's school in the autumn of 1814.1

He remained in this position until 1818, though he found the work "uncongenial" and often felt frustrated by the duties that kept him from his music. Later, in 1824, he returned to a teaching post with the Esterházy family when he was in desperate need of money. Throughout his life, while he devoted himself almost entirely to composition, he relied on various sources of income, including publishers' fees and occasional teaching, to sustain himself.123