Ever since the dawn of the Industrial Revolution that took place in the UK back in 1760, the rags-to-riches tale has been a real thing. Not in the way it is typically sold.
For example, as Malcolm Gladwell brilliantly showed in his book Outliers, jumping from poverty to riches is rare and nearly always a result of luck.
But moving from lower class to middle class, or from middle class to upper class, has not been rare and has mostly been the result of hard work.
This can be seen in the evidence. For example, throughout most of the 1900s, class jumping was extremely common across Europe, the UK, and North America.