My dad had a 10th grade education and worked at a paper box factory and was able to be the sole provider in a family with four kids. They had a house, a cottage at the lake that they paid cash for, a car, and cable colour TV.
But taxes were really, really low then. Because there were no public pensions, and very, very little in the way of other social services. Also, health care costs were far lower since we had almost none of the expensive high-tech stuff we have now. Half the population mostly didn't work, which led to that old supply/demand rule on wages. And he didn't have to compete with workers in China or India or automation. He probably wasn't paying anything for cell phone service or to his internet provider, or for multi tiered cable. Electricity was dirt cheap, as was gasoline, as was insurance. Oh, and the population was half what it is today, so land was a lot less valuable, and you could find cottages really cheap.
Then the boomers came along and did even better.
The biggest crime our boomers committed was they were willing to take all the goodies people like Trudeau offered them, but unwilling to pay for them. They wanted the pensions, but didn't want to pay for them. They wanted all the new social programs but low taxes. When their parents had a lot of kids they built schools. When the boomers had kids they said 'screw that, I ain't paying' and let them use portables. The boomers wanted to have their cake and eat it too, and they stuck the following generations with the bill.
But... we weren't talking about Canada's economy or lifestyle but 'the world' and 'the world' is by almost every measure infinitely better off today than it was forty or fifty years ago.