How did British philosopher Herbert Spencer justify the accumulation of mass wealth?

Herbert Spencer justified the accumulation of mass wealth through his application of Darwinian principles to society, famously coining the term "survival of the fittest." He argued that wealth accumulation was a natural outcome of competition and social evolution, where those who succeeded economically were deemed more capable and better suited for survival. Spencer believed that this process ultimately benefited society by promoting progress and improvement, as the wealthy were seen as innovators and leaders who could drive advancements. Thus, he viewed the concentration of wealth as a positive force in the development of civilization.