That's true, but "much harder" != "impossible". If you print enough dollars, there will come a point at which it will stop being the world's reserve currency. The only way to find out where that point is is to actually cross it. That will be a very painful experiment to conduct. If we ever get to that point, the world will learn the meaning of the word "hysteresis".

Well, stocks at the moment. The real value of U.S. stocks has not risen 20% in one month. What has really happened is that the U.S. dollar has lost 20% of its value relative to stocks. Inflation takes a long time to work its way into the economy at large, and it is possible that it won't happen. We managed to avoid it after 2008, but back then we had some very competent people running the show. I'm less sanguine about that this time around. My reading of the tea leaves is that the Trump administration will prop up stock prices by whatever means necessary because they believe (probably correctly) that many people will vote according to the bottom line of their 401ks.

But it is simply not possible to keep pumping currency into a shrinking economy without producing inflation. Sooner or later the law of supply and demand will catch up with you. The only question is whether it will happen before or after November.

That's because the economy has grown more or less apace with the money supply (or, more accurately, because the Fed has controlled the growth of the money supply to keep pace with the economy). Now we are pumping cash into a shrinking economy. You can't do that for very long without producing inflation.