The reason it is so feared is because it's next to impossible to contain once it starts without causing massive economic hardship. In fact, the Fed could likel

The reason it is so feared is because it's next to impossible to contain once it starts without causing massive economic hardship. In fact, the Fed could likely do next to nothing about inflation with our country's current debt levels. Even at a historically average rate of 8%, our federal government would either go bankrupt, cut most spending, or massively raise taxes, causing a severe economic retraction. (Our $26T in debt would require half of the entire federal budget to service our debt at such rates.) Many of our largest corporations would also fold, unable to service their massive debts. It'd be a disaster. That's why people fear runaway inflation, even if it hasn't been a problem for several decades. Once you can identify it as a problem, it's too late.