50% wage growth over fifty years whilst Britain’s running the largest empire in history? Compare that to the United States over the same period. The US saw 60% real wage growth from 1860-1890 with no empire whatsoever. If imperial profits were trickling down, you’d expect Britain to outpace non-imperial industrialising nations. It didn’t, if anything it was worse.
The literacy and life expectancy gains you’re citing came from industrialisation and public health reforms, not imperial dividends. Meanwhile the landed gentry who actually controlled the imperial trade were getting obscenely wealthy.
Life expectancy of 50 in 1900 still meant working-class Londoners in overcrowded tenements with open sewers, whilst their supposed countrymen lived in townhouses with servants. The Victorian poor saw industrial revolution gains, not imperial ones.