They’re everyday workers who clocked into their jobs day in and day out, all the while faithfully socking away money for the time, decades out, when they finally retired. And now they’re millionaires. Fidelity Investments announced this week that the number of people with seven figures in their 401(k) accounts jumped 20% from September to the end of December. That struck a major chord with readers — nearly 4,000 of you weighed in on the news of so many regular folks saving for retirement and reaching the million-dollar mountaintop.