The new Sam Wilson Captain America #1 by Nick Spencer has Captain America sever ties with SHIELD and the Government. Cap is now a free agent fighting for those who ask for help (well, reasonable requests, not flying into sporting events or fighting over cable bills).
Body armor for sidekicks and private jets cost money. Cap stated he was setting up crowdfunding in order to fund his hero activities like a political campaign. Would it be legal to crowdfund crime fighting?
The law does not favor vigilantism. Society does not want people taking the law into their own hands. Starting a crowdfunding campaign to do something illegal is problematic at best and a conspiracy at worst.
Captain America #1 puts two different forms of vigilantism into conflict with Sam Wilson fighting a terrorist-vigilante-border-patrol militia group. It should be noted that boarder security and combating illegal immigration are exclusively Federal responsibilities.
The “Sons of the Serpent” are a terrorist organization engaging in illegal vigilante boarder patrol activities. Their goal was to kill those entering the United States illegally. Captain America goes to Arizona to investigate a missing person who was either killed or kidnapped by the Sons of the Serpent, resulting in a confrontation.
Murder in the name of boarder security is just plain illegal. There is absolutely no argument terrorists could make that they are acting on behalf of the United States. Captain America has a strong argument that his actions were in the defense of others to stop terrorists, because a reasonable person would believe physical force was immediately necessary to protect those illegally crossing the border from being murdered by terrorists in costumes with high-powered weapons. A.R.S. § 13-404.
The issue of whether Captain America can run a Super Pack to crowdfund his super-hero activities presents some funky legal issues. Being a super-hero is not like the Red Cross responding to a natural disaster, but actively seeking out criminals to engage in law enforcement activities. No one can crowdfund an illegal activity. There is a strong argument that raising money to engage in super-hero activity would violate RICO. There is also a chance that if Cap is fighting the government, his crowdfunding is actually a form of insurrection. As such, everyone supporting it would be part of a vast conspiracy.
Should Captain America fight terrorists? Yes. Protecting the poor, huddled masses, from terrorists is something Americans proudly do (responding to illegal border crossings is a different issue for the government, but one that does NOT involve murder by private citizens).
Can Captain America raise money like a political action committee for that purpose? No, but he could if it was for his legal defense or to aid those who were the victims of super-villains, then the crowdfunding would be for a legitimate purpose that would not be vigilantism.