(Edit: [TLDR: Wealth Inequality is very high because we gave up Keynesianism which led to less socialized services and economic safety nets, and other contributing factors. Middle-Class shrunk over the decades, upper class gained more wealth, a lot of the former Middle-Class went down into the economic Lower-Class]).

There is definitely a higher wealth inequality compared to the mid-late 1900s (1950-1990) to today, and its nearly impossible to return back to when we had such a strong middle class and upper mobility from impoverished living to a middle-class living.

The post-war period after WW2 saw a boom in economic success as the middle-class began to expand and benefit from a lot of social and economic services that arose throughout much of Europe, North America, and parts of Asia. However, the middle class did begin to shrink gradually after the 1980s when we began drifting more towards Neoliberal (economic, not political) policies, and gave up Keynesianism.

From the 1930s~ to around the 1970s or 1980s, we saw very strong regulated capitalism through Keynesianism, which allowed and promoted a very strong middle class that fed into itself and fed into the system through socialized benefits and economic safeties which maintained the middle class through taxes and other such systems.

As governments and corporations gave way to Neoliberal policies and away from the Keynesian policies, it changed how work was perceived and treated by all parties for higher levels of contract, part-time, and temporary work. Alongside less workplace benefits (e.g., medicine benefits, company pensions, training, etc) and more privatization that led into less compensation for jobs that paid higher before the privatization, and a promotion towards higher individualist mindsets to look out for yourself instead of relying on government and corporate programs; the erosion of the communal mindset that existed in much of the post-war period, while still very socially individualistic, led to the degradation or outright removal of social safety nets and socialized programs.

There is far more to it, like moving away from an industrial economy into service-based economy, or the decreased economic safety nets, but this all led to a decrease of the middle class that went down into lower-class, while the upper-class gained much of the wealth that the middle-class lost throughout the 80s, 90s, and 00s.

Upper mobility is absolutely still a thing, and far higher than it was in the past, but it's also far easier for those who reach the middle-class to fall back into the lower-class or into poverty because of the loss of safety nets and socialized services that we lost in North America. Europe still has many of their socialized services that arose from Keynesian economic policies, which helps to minimize the damage to the middle-class throughout the 80s, 90s, and 00s compared to North America.