Adams was pretty clearly wrong.
There are numerous examples of peoples losing their liberty through conquest or usurpation by one group or another, and then regaining it. In fact, with rare exceptions any people that is free today has been through such events.
Of course, doing so usually requires going through one or more cycles of war and/or revolution.
France, England (Civil War), Ireland, Germany, Poland, Russia, Finland, the Baltics, Czech Republic, Mexico and just about any Latin American country you care to name, Romania, Croatia, Italy, Spain, Portugal, etc.
You apparently do not read the same history that I do.
Adams was NOT wrong.
He was historically, and biblically - correct and prophetic.
There is NO instance I can find in history of a people having liberty and losing it to their own gluttony, hedonism and indifference, ever regaining what they lost.
What comes much later after a people go into bondage - is totally different than what they once had. Most never live to see a semblance of freedom again.
Once the anomaly of America is removed from the world stage - what we understood of liberty, will never appear again. That too - is biblical and historical in context.
I’ll take the wisdom of the Founders over what passes as knowledge and wisdom today.