There isn't an absolute decline in the West. Things are better than they were in the 60s, 70s, and 80s. Medicine is better, technology is better, homes are better, cars are better, everything is better. I can't think of any Western nations where things have objectively stagnated or regressed in the last 40-50 years.
Maybe there's been some relative decline, but that's offset by the US being dramatically more powerful in the 21st century than the early 20th, and doesn't matter because the rest of the World is catching up to us rather than us regressing to their levels. China has lifted hundreds of millions of people from poverty, which is a great accomplishment, and doesn't mean that we are worse off. It's certainly better than the 70s or the 80s when the Soviets might've just decided to kill us all.
You'll note that Germany and France both see declining "deaths of despair," but AfD captured parliament seats just last weekend, and the National Front in France has been doing better than they ever have been. I don't see Australia as having a growing far-right movement compared to either of those nations. Based on Wiki perusal, this Xenophon team is the newest party, and is roughly equivalent to Michael Bloomberg deciding to start his own party.
Privatization, deregulation, and free trade, make the West better off. There are some losers from trade, as there are losers with any policy. They happen to be geographically concentrated in swing states.