Credible people have been predicting run away inflation for US currency for over 40 years, and increasingly over the past 10 years as most financial gurus have been assuring us that interest rates could not possibly go any lower. they were wrong.
Economic collapse might also lead to deflation as it has the past 20 years in Japan and the last 4 years in the USA. In this case people with big mortgages and other debt have lost bigtime.
It is easy to make tons of money if you know future inflation and interest rates. Noboby knows for certain and that is what makes a market.
What you are missing is that you could be wrong and the opposite could occur and you would lose.