There are lots of recent examples of the left's commitment to their causes.
Staging the Winsconsin statehouse protest was wrongheaded and annoying but it took guts.
OWS camping out in public spaces for months on end was foolish and a blight, but it took guts.
Getting arrested protesting outside the Sudenese embassy in WDC took guts, and there are many more examples.
So no, I don't think a 'lack of guts' is any kind of problem for the left.
You're talking about street protests and such, which isn't so much a display of "guts" (as I put it), but more a display of passionate commitment to their pet social causes.
Our side has displayed the same level of commitment to social causes that matter to us. Note the many Tea Party rallies, and Overpasses protests in the last few years.
No, when I say "guts", I'm referring to the sort of backbone and courage it takes to fight a real war. The left in the west has shown time and time again that they don't have the stomach to face a determined foe with unflinching grit and determination.
Look at every liberal administration in the western world since 1945, and you can't find a single one that ever conducted a military campaign that was designed and executed with the sort of no-holds-barred aggression which is required to achieve real victory. Not one.
Observe how western liberal governments conduct their international diplomacy during peacetime. They ordinarily bend over backwards to appease violent dictators and murderous regimes, while turning their backs on their real allies. Their friends in the press and academia are no different, and usually play the part of spinmeisters and propagandists for the yellow bellied cowards in government.
In short, the political left can't throw a punch and mean it. If the political right ever stood on their hind legs and acted like men, the left would back right down. It's what they do when they're confronted by real anger and opposition.
And if a day should ever come when several states secede from the union, you can bet your bottom dollar that the weasels running the feral government in Washington won't have the guts to execute a military campaign to squash it through force. Not if they're convinced that the red states will fight back with everything they've got.
They're really good at killing defenseless women and children and unarmed men, but they shrink in the face of a well armed and determined enemy.