There were about 4,000 millionaires in the United States in 1900. Back then, if one family invested $5 million passively in the broader US stock market and spent from it reasonably (about 2% of their wealth each year), they would have $16 billion today. Approximately 16,000 billionaire households would exist today if a quarter of those families had done the same.

Despite this, Forbes estimates there are only about 730 billionaires in the country, and few of them inherited wealth from their parents. Fewer than 10% of the current billionaires descend from those on the first Forbes’ rich list, published in 1982.

“The Missing Billionaires,” a book co-authored with James White by Victor Haghani, co-founder of wealth management firm Elm Partners, attempts to answer that question.

According to Haghani, the answer lies in the way people invest. Instead of focusing on how much to buy and sell, they tend to focus too much on which stocks to buy and sell.

As a first-hand witness, Haghani has first-hand knowledge. In the 1990s, he co-founded Long-Term Capital Management (LTCM) and brought Wall Street returns of 30% a year.

He was until he wasn’t.

As a result of the Russian crisis in 1998, the highly leveraged LTCM lost $4.6 billion in less than four months. Fed officials gathered the world’s most powerful banks and orchestrated a $3.65 billion recapitalization, but the fund was eventually liquidated.