Nicholas Hunt/Getty ImagesFor high-income earners, the 401(k) has proved to be a successful wealth-builder — there's even a record number of 401(k) millionaires. Ted Benna, now 84, helped create the ubiquitous workplace retirement plan about 40 years ago. Must ReadNow he says 401(k) plans have become too costly and complex. And they don't benefit the lower-income workers — truckers, retail staff, hourly workers — who need them most. "The 401(k) isn't working really well now for many middle- and lower-income employees," Benna told Bloomberg.