False again. The value of the money didn't change, the purchasing power of the money changed. The paper is still worth $150,000 regardless of year. The purchasing power of $150,000 will go up or down as inflation and de-inflation change the purchasing power of the paper money.
Going back to when you grandfather was your age, that same $12 (assuming a $10 bill and 2 $1 bills) would still be worth $12 in todays economy. However, the purchasing power of $12 is vastly less today than it was 90 years ago.
Purchasing power is where we derive things like the CPI, so we can track how it changes over time.