You don’t have to go back many generations to see that compared to today almost everyone played on hard mode.
Hard mode is comparable across the same game. Those in 1800 played 1800s game, those in Nigeria play the Nigerian game, etc.
You wouldn't consider it much of a success if a person with huge work, skills, and effort got themselves to 1800-era middle class possessions TODAY, would you?
Our ancestors struggled in a much harsher world and got us to a point where we can enjoy easy mode.
Why can’t the poorest Americans do the same?
They struggled in an era of economic upward momentum, much mobility, job creation, with a population boom, and when the US emerged as global leader. And from 30s to 70s, in a much more labor and working class friendly climate, when lots of protections and rights were established (the 8-hour work day, pensions, minimum wages, equal rights for women and foreign workers, work safety, etc).
Not on an era of stagnant wages, job outsourcing, automation, over-concentration of money to too few hands, precariousness, eroded labour rights, when other countries emerge as global leaders, and so on.
When playing life's levels, it's not just the conditions you meet that matter, it's the momentum of the whole game environment too. If the game environment constantly upgrades, gives you more guns, ammo, etc, it's easier than playing easier initial conditions but seeing very slow or negative game environment progress.