As the above evidence actually shows, purchasing power is not dwindling, it is actually stable.
Furthermore, purchasing power (which is stable and not increasing) is not the end-all.
People that abandoned the Weimar Republic over actual and hard drop in purchasing power (=inability to buy food, not inability to buy a new iphone every 2 years) found themselves under the Nazi regime, HH.
People that were waving the flag of revolution in 1917 found themselves under Stalinist USSR soon after. And People that rode the tanks with Yeltsin in the death-throes of USSR... found themselves sending their daughters and wives as strippers and prostitutes in Europe later on.
People that wanted to overthrow the corrupt and inefficient Kazrai Regime are living now under the Taliban.
Long story short: No. What you say is dangerous and more often than not, leads to disaster for the average Joe.