Donald Trump borrowed money from his dad in the late 1970's to start a business, then inherited his father's empire altogether in the 1980's. He took the lion's share of his father's wealth. That's 200 million in 1982, with purchasing power of 500 to 1 billion today. His wealth had not kept pace with the growth of S&P 500 Index even with all his "deals", thus he's not that great of a businessman.
Certainly in 1982 index fund was not available, but it appeared as IPS in 1989. Last time I checked, 1989 is still considered 1980's, unless you can't count the year properly. There was nothing preventing him from investing in diversified portfolio in the S&P 500 index back in 1982 either, doing so would allow him to be worth twice as much as today.
You're either not very good at this or being dishonest, maybe both.