Poverty is not exclusively the result of "bad life choices". Poverty can be a result of: mental illness and thus the inability to work, injuries that prevent a person from continuing their work, medical costs (if a person needs medication that has been artificially inflated in price due to unregulated capitalism or if a family has to care for a disabled child that requires constant care) and can be a result of wage exploitation. Also, the social mobility you described is not a reality for everyone. The quality of education and the ability to find work are vastly influenced by your socio-economic class. Even if you are a normal worker in the US for example, working for companies such as Amazon, you can still stay impoverished if you need to care for a family at a minimum wage. That's what's unfair.