Very plainly ask an old person if their standard of living or anyone else’s they know has meaningfully improved since the 70s (except for cheaper TVs). Don’t do anything to indicate it might be a politically loaded question or that you might use their answer for an argument or agenda. Most likely, if they’re not motivated to lie about it, they’ll tell you no.*

*If they’re caught in the Trump Reality Distortion Field, they’ll insist that 2016 to 2020 were the best years of modern history.