Just who would the "unqualified people" be? Those who refuse to pay a another person,state,or federal government money in order to use their rights?
As for the economic issue, maybe the day will come when the court rules that the government must provide a self-defense weapon for use in one's home to those who can't otherwise afford one, similar to the way government has to provide an attorney to a person charged with a crime if the person cannot afford one.
As to your other questions, to give up a right you have to have a right in the first place. The SCOTUS has made it very clear that the definition of the right to bear arms does not mean "everyone, everywhere, any gun, all the time."
As for "qualified" people it is more a matter of determining who is "not qualified" for constitutional purposes, or more accurately, who is not covered by the scope of the Second Amendment right to bear arms. Those "unqualified" people simply don't have a right under the Second Amendment to be "given up." One can't give up what they don't have in the first place.
People with a history of violence, drug abusers, and alcoholics might be some of those who don't have a right to bear arms. Moreover, even if they were within the scope of the right to bear arms, they might be deemed "unqualified" under one of the other three criteria identified by
Eugene Volokh in his writings on assessing the constitutionality of gun laws post-McDonald:
1. Limited Scope: A restriction might not be covered by the constitutional text, the original meaning of the text, the traditional understanding of the text’s scope, the background legal principles establishing who is entitled to various rights, or the categorical exceptions set forth by binding precedent (such as Heller’s statement that bans on gun possession by felons, bans on concealed carry, and several other kinds of gun controls are constitutional).
2. Slight Burden: A restriction might only slightly interfere with rightholders’ ability to get the benefits that the right secures, and thus might be a burden that doesn’t rise to the level of unconstitutionally “infring[ing]” the right
3. Reducing Danger: A restriction might reduce various dangers (in the case of arms possession, chiefly the dangers of crime and injury) so much that the court concludes that even a substantial burden is justified.
4. Government as Proprietor: The government might have special power stemming from its authority as proprietor, employer, or subsidizer to control behavior on its property or behavior by recipients of its property.
As Volokh points out, these are not simplistic issues resolved by shouting "shall not be infringed" because under the first criteria there is nothing to be infringed. It is only if we reach the second, third and fourth criteria where "infringement" becomes and issue.