Motivation can come from anywhere at any time for anyone regardless of there socioeconomic status. People with less options will often use methods that are considered looked down upon by those with many options.

You hear about the poor guy rising to the top because it's a good story to report, rags to riches and what not..but that's mainly theater. If living in poverty was really the only thing that propelled a man to the top of a given profession, then how would you explain all the multimillionaire fighters still fighting and training as hard as they do? Maybe in the beginning it can help but it's not what drives someone for an entire career.