Many Americans now face retirement, hearts full of dreams, bank accounts full of nothing. For them, those Wall Street ads showing silver-haired couples sailing warm blue seas may seem aspirations beyond their grasp. Instead, they may find themselves the 72-year-old hired to drive the platinum couple from the airport to the docks.

Some 45 percent of Americans have zero saved for retirement, according to the National Institute on Retirement Security. Why would that be?

The reasons are diverse. The problem may be stagnating wages, an expensive medical crisis or divorce that chopped household income in half. Or while collecting paychecks, they didn't save enough, invested unwisely and spent too much on vacations, cars and pricey luxuries.

A big reason is the near disappearance of the traditional pension plan. It made saving for retirement a no-brainer. Employees didn't have to decide how much, if any, of their paycheck to set aside. They didn't do the investing. The company did it all. On retirement, former employees would be sent a pension check every month, possibly for the rest of their lives.

The 401(k) plan has taken its place. This is a deal whereby workers elect to move a certain amount out of their paychecks every week and into a retirement account. Participants usually have a say in how the money is invested. And the 401(k) is a deal − even though investment companies often take a too-big chunk in fees. The employer may match some of the contributions. And the earnings deposited in the 401(k) are not taxed. You pay taxes only when you retire and withdraw the funds.

Though 80 percent of workers have access to a 401(k), only 61 percent put anything in. And many who do vastly underestimate what they'll need and contribute far too little.

Whether they have other savings or not, Americans know that Social Security is there as a backstop. (Don't let anyone tell you the program is going down.) Social Security is beautifully simple, but even here, people make mistakes. For one, they start collecting benefits too early. Consider the 61-year-old entitled to $1,000 a month at the full retirement age of 66. If that person starts collecting early at 62, the monthly check drops to $750. By waiting until age 70, the benefit jumps to $1,350. The difference between dipping in early and late is, starting at 70, $600 a month for the rest of one's life.

In a recent poll of Americans over age 50, 4 in 10 said they plan to start collecting Social Security benefits early. Less than 9 percent said they'll hold off until 70.

On the spending and borrowing side, the housing bubble of the 2000s fostered some bad habits. As real estate values rose, people started seeing their home as the pot of gold funding their retirement. They figured they didn't need other savings.

Many also started treating their homes like piggy banks. As home prices rose, they refinanced their mortgages, borrowing more so they could take cash out for whatever. Home equity loans were another means of doing that. Mine came with a checkbook, meaning I could pay the electric bill by reducing my home equity (the part of the house that I, not the bank, owned).

Toward the end of last decade, the bubble popped, and for many, the magic money vanished.

Savvy Americans with high net worth seem quite able to guarantee clear sailing in retirement. Others who don't plan, can't plan or are in too desperate straits to put anything aside may end up working for the rest of their lives. That presupposes they can work. What if they can't?

Froma Harrop's column is distributed by Creators Syndicate.