“A recent poll by Reuters/Ipsos found that only a quarter of all Americans support the shutdown. Only 35 percent said they favored including money for the wall in a spending bill… About 800,000 federal employees, and the citizens who depend on them, are being hurt for an empty political stunt.”
New York Times

“Current White House aides acknowledge privately that a wall will not adequately address the record surge of immigrant families at the border — most of whom surrender to authorities in hopes of winning asylum protections… [But] with both sides entrenched, there has been little bipartisan urgency to examine the relatively narrow set of legal and administrative changes that could potentially make a difference in slowing illegal migration or improving conditions for families who arrive at the border.”
Washington Post

“There's actually a bipartisan deal within reach -- something like the Dreamers-for-border-security proposal that failed narrowly in the Senate last February… people want a functioning legal immigration system, smarter security at ports of entry and along the border, and the opportunity for undocumented men and women who are already in the country and contributing to attain citizenship… The seeds of a solution are planted. Mr. President, it's time to make a deal.”
CNN

“The government shutdown is already making us more insecure… there has been an increase in TSA employees calling in sick to work since the shutdown started… TSA agents who do show up to work [may be] stretched thin if they have to work extra shifts to account for colleagues who have to miss work, which means that the odds of detecting a threat may decrease. This is a clarion call to our enemies to take advantage of understaffing and to try to exploit any gaps in our security posture.”
CNN

Moreover, in a prolonged shutdown, “food stamps, housing assistance, and tax refunds are all at risk… some 38 million families who rely on SNAP could go entirely without assistance [in February]… rental assistance payments could cease… the people who stand to lose the most are America’s poorest families who rely on government assistance to get by.”
Rolling Stone

Finally, some note that “the world’s confidence in the U.S. government — and by extension, the U.S. economy — depends on seeing the American polity as basically functional…

"In the Trump era, it’s becoming commonplace to assume that the economic fundamentals that make the U.S. attractive for investment will remain unaffected by our political dysfunction. That’s a mistake that confuses short-term predictions with the long-term institutional structures being damaged… a long-term shutdown will be costly — not today or tomorrow, but soon, and for the rest of our lives.”
Bloomberg