This math is grossly oversimplified...you're assuming zero interest. I'm on a train and can't do the math right now, but compounding interest + other variables like employer 401k contributions, tax shelters, etc make a huge difference when doing this calculation.

Interest rates won't hover near 0% forever.

Getting returns of 2% a year, drops that down to $1300/month.

Still steep for most people, but much more achievable, and 2% return is pretty conservative.

Of course you would not save for your retirement using a savings account.