 Gates became the first American to take the top spot of the world's billionaires in 1995 with a net worth of $12.5 billion, and he remained there during the dot-com bubble's height in 1999 when his fortune peaked at $90 billion.After the dot-com bubble started to collapse in 2000, his wealth dropped to $60 billion, although he remained at the top of the list.The dot-com bubble created the most paper wealth for some billionaires.