Your friend suffers from educational abuse

It’s propaganda. It is true that deflation would collapse the current system because it is debt based.

Once you get passed the collapse- deflation creates savers, not consumers. An economy based on savers would stop needless consumption of poor products. It would stop the theft of people’s savings and the endless rat race that we are stuck in due to inflation. It would slow down the wealth gap as inflation benefits the wealthiest the most because they have the most access to debt.

He learned Keynesian economics through a state sponsored school which supports government spending through inflation. That's why most economists think like him. It's highly likely he's brainwashed and he won't listen to you. I'd ask him how is it that America saw one of the greatest economic expansions under the gold standard without inflation. Might also point out that inflating the money supply is quite literally stealing and if your or I did it we go to jail. It's a moral issue, a system based on theft. However, deflation would make the current system blow up due to all of the debt, so that's part of the perspective he's coming from and I doubt he'll see out of that if he thinks Keynesians are the smart ones.

The biggest obstacle to a deflationary system, would be getting people to accept pay cuts instead of raises. And if you really think through the deflationary model, you’ll see that’s precisely what it implies. We are simply not wired that way.

Most economists are pretty dumb and smoke meth, why would you believe this