It doesn't look similar at all; you should examine the chart again. To quote from this article: https://www.washingtonpost.com/business/2019/12/03/precariousness-modern-young-adulthood-one-chart/

"As the chart above shows, baby boomers — those born between 1946 and 1964 — collectively owned 21 percent of the nation’s wealth by the time their generation hit a median age of 35 in 1990."

"Generation X (born from 1965 to 1980) came of age during the era of wage stagnation and growing inequality ushered in by the 1970s and ’80s. When the typical Gen Xer reached 35 in 2008, his or her share of the nation’s wealth was just 9 percent, less than half that of boomers at a comparable point in life."

"Millennials haven’t hit the 35 mark yet — that won’t happen until about 2023 — but their financial situation is relatively dire. They own just 3.2 percent of the nation’s wealth. To catch up to Gen Xers, they’d need to triple their wealth in just four years. To reach boomers, their net worth would need a sevenfold jump."

Part of this is the fact that inheritance taxes and income taxes on the rich are comparatively low and/or effectively evaded in many places, inequality in who gets which kinds of jobs, and so forth, but there are many other reasons as well.