The low interest rates we've experienced over the last decade, which have only gotten lower as of late, have actually blown up retirement plans.
Used to be, $500,000 saved at 8% meant you could retire off the $40k interest + social security. It also meant that growing a savings account into $500,000 was not out of reach, even on a modest income. This was the plan many people in the 60's, 70's, 80's worked towards.
Now, getting to $500k in savings is much more difficult as compound interest is so much lower. And if you happened to get there, you'd earn a whopping $5000, maybe less, in interest per year.