Average investors are frustrated that the U.S. government is no longer among the world’s most creditworthy, and fear today’s stock plunge may not be the end.

And even though many suffered steep losses when the market tumbled three years ago, some now appear more willing to ride things out, figuring their portfolios will eventually recover.

The question is whether they’ll be patient enough to stick with their plans. Any market rebound seems distant, given the spate of bad news about the economy, and debt problems here and in Europe.

The hope is that Standard & Poor’s downgrade of the U.S. debt rating could spur Congress to take the painful steps needed to ultimately strengthen the economy

“I’m sort of glad it happened,” says Matt Moscardi, a 32-year-old researcher with a Boston financial services company. “My investments might get killed in the short-term, but there’s some serious dysfunction in our fiscal policy.”

S&P on Friday cut its credit rating for long-term U.S. government debt by one notch, from AAA, the highest rating, to AA+.

The Dow Jones industrial average had already plunged 10 percent since late July, and it responded to news of S&P’s move by tumbling more than 250 points after today’s opening bell. The decline worsened by mid-afternoon, to 517 points, down 4.5 percent. As investors sought safety, the price of gold topped $1,700 an ounce for the first time.

President Obama urged calm, saying in a televised address that financial markets around the world continue to believe the U.S. is creditworthy.

Corporate profits remain strong, which is a key reason why the Dow remains about 70 percent above its March 2009 low. Yet the recent decline appears to be reflection of what many average Americans have felt since the recession officially ended two years ago. They continue to face persistently high unemployment, flat wages, a stalled housing recovery, and fear that Washington has only begun to squarely address its debt problems.

Many investors were confident that they’ve adequately protected their investments for another rough stretch. After the 2008 financial crisis, Carol Clemens, a 64-year-old retiree from Edmond, Okla., loaded her portfolio with dividend-paying U.S. and foreign stocks. With corporate earnings remaining healthy, she doesn’t have any immediate plans to sell.

“I expect there are still lemmings left who must run for the cliff, but I will not be among them,” Clemens says.

Her reaction to S&P’s debt downgrade: “I’m just glad that one of the ratings agencies finally had the gumption to take a stand, and tell Congress and the president: ‘You’ve gone too far, guys. It’s time to get real.'”

Some investors had moved quickly to reduce their risk as Congress approached the Aug. 2 deadline for reaching a debt ceiling deal, avoiding a potential default. Pat Rosenheim, a 57-year-old former phone company technician from Danvers, Mass., sold nearly all his stock and mutual fund holdings on July 29th, as a deal remained in doubt.

Now, his portfolio is about 90 percent in cash, and he’s not looking to jump back in.

“I’m thinking ‘Gee, isn’t it great to be almost all in cash right now,'” Rosenheim says. “In the end, it all boils down to really only one thing: Can you sleep at night?”

David Savage, 51, of Naugatuck, Conn., a manager of a demolition equipment company, is taking a ride-it-out approach that most financial planners recommend, provided an investor has a sensible long-term plan. Savage doesn’t plan any changes to a 401(k) portfolio invested primarily in stock index funds.

“One should never underestimate the investor’s ability to panic,” Savage says.

He expects a market recovery, and doesn’t believe the economy will slip back into recession.

“After all, how many companies will have their day-to-day business truly affected by what has happened in the last few days?” he says. “Companies that have been on the comeback will continue to operate the same today as they did last week.”

Still, some investors are active, regarding today’s market’s decline as a buying opportunity.

“I’ll be watching for the panic to turn, because a crisis is a terrible thing to waste,” says Dick Bristol, a retired Air Force major and dividend-stock investor from Biloxi, Miss.

While Bristol fears the market decline will be prolonged, the 73-year-old believes S&P “has done us a favor” by potentially pushing the U.S. toward greater fiscal responsibility.

Johanna Schulman, a certified financial planner with Ameriprise Financial Services in Cambridge, Mass., says the individual investors she advises didn’t flood her with phone calls and emails over the weekend. Those who contacted her “recognized they are faced with very limited choices,” Schulman says.

“They can stay the course, as they know they are supposed to,” she says, “Or they can sell stocks and rush into something safe — a course they know they are not supposed to take, and one that risks missing out on whatever recovery may lie ahead.”

Schulman told clients to expect volatility, while keeping long-range plans in mind.

“There’s frustration knowing there are no easy answers, and that if one follows the conventional advice, it’s a painful prescription,” she says.

Cass Chappell, a planner with Chappell, Mayfield & Associates in Atlanta, recently heard from several clients “who just wanted to be calmed down.”

Most also were clients in 2008, and have embraced Chappell’s belief that successful investing means avoiding the temptation to overhaul a portfolio in response to day-to-day news.

Yet investors also recognize the role of psychology, where day-to-day sentiment of the investing public can overwhelm the underlying business strengths of corporate America, such as its earnings prospects.

“I don’t think investors are worried about the downgrade,” says Charles Lewis Sizemore, chief investment officer with Dallas-based Sizemore Capital Management. “It’s more a case of investors being afraid of each other.”

He says his clients are edgy like so many others, and vulnerable to making rash decisions. That’s because S&P’s downgrade seems like a personal affront.

“Americans are used to walking around with their head held high,” Sizemore says. “And when your credit gets downgraded like that, it’s sort of emasculating to the national psyche. It affects people’s moods.”

And with emotions running high, the risk of a misstep is magnified by technology.

Investors have immediate access to their accounts over the Internet, and with the push of a button, can sell out quickly, notes Adam Bold, founder of The Mutual Fund Store, a manager of $6.5 billion based in Overland Park, Kan.

“For many people who make these decisions on their own, it’s all or nothing,” Bold says.

“It’s best not to make dramatic changes on days when we have high volatility,” he says. “Investors would be very well-suited, regardless of what’s going on, to wait a day or two.”