For close to 300 years, inflation in the US remained very subdued. Small spurts occurred around major wars (Revolutionary, Civil, WW1, etc), but after each, inflation quickly trended back down to its long-term baseline. If you lived during this stretch of time, your money had roughly the same purchasing power your great-grandfather’s did.
But something changed after inflation spiked yet again during World War 2. With the permanent mobilization of the military industrial complex and the start of the decades-long Cold War, combined with a related acceleration in government deficit spending, inflation did not come back down. It remained elevated, and in fact, rose further.