The US Dollar is not worth anywhere near what it was back at the top of the last bull market in gold. The yellow line is the gold price adjusted for the depreciation of the dollar since the top of the last gold bull market.
Roughly speaking a 1980 US dollar buys only about 1/17 th of what it used to buy. So, gold needs to go up about 5 1/2 times before its price equals, in purchasing power terms, its old 1980 price at the top of the last bull market. $660 times 5.5 = $3,630. But between now and when gold gets to $3,630 there will be even more US Dollars in the world. So count on an even higher gold nominal price.
"Like gold, U.S. dollars have value only to the extent that they are strictly limited in supply. But the U.S. government has a technology, called a printing press (or, today, its electronic equivalent), that allows it to produce as many U.S. dollars as it wishes at essentially no cost. By increasing the number of U.S. dollars in circulation, or even by credibly threatening to do so, the U.S. government can also reduce the value of a dollar in terms of goods and services, which is equivalent to raising the prices in dollars of those goods and services. We conclude that, under a paper-money system, a determined government can always generate higher spending and hence positive inflation." - Ben Bernanke remarks before the National Economists Club, Washington, D.C. November 21, 2002