Well, you're partially correct. Definitely being happy with what you have makes you "richer" but you're wrong about why average people aren't making more money since the 1980s... in the US.

Since the 1970s in the US, corporations have been allowed more and more to "donate to" (actually = "invest in") politicians. They bought elections and thus laws. In the Reagan years, this brought a huge drop in the highest marginal tax rates, a huge push against unions, and a huge shift in the total tax burden from corporations to individuals that continues to this day.

The result is that productivity has continued to increase, but the additional wealth all goes to those at the top of the income chart. Since 1975 the top 1% has taken $50 trillion (yes, with a "t") from the bottom 90%. The average worker today ($50k/year) would earn $92k-$102k/year (depending on how you calculate inflation).

The 1% has stolen roughly half the wages from the bottom 90% through political corruption over the last 40+ years. That is why people have a hard time affording a middle class lifestyle. Their wages have been stolen by the ultra-wealthy.