Certainly it is possible to make nouns from adjectives, but in this case "the poor" is already a noun. To paraphrase the common translation of a quote from Anatole France:
In its majestic equality, the law forbids the rich and the poor alike to sleep under bridges, beg in the streets and steal loaves of bread.
In this case "the poor" refers to the general class of people who are poor. "Poverty" on the other hand, refers to the condition of being poor, which is not the same thing.
In the same way, someone who is "homeless* belongs to the class of people referred to as "the homeless". "Homelessness" is the noun describing that condition. Similarly the final stanza in the United States national anthem:
o'er (over) the land of the free and the home of the brave.
Where "the free" and "the brave" represent the group of people characterized by freedom and bravery.
While "the poor" is a common descriptive noun, "the poors" would be considered slang, and sounds derogatory. This is circumstantial and based on context. Other created nouns might sound just fine:
Adopters of new technology can be divided into two groups of those who are optimistic and those who are skeptical -- or as I like to call them, the confidents and the hesitants.
In this case the adjectives describe the essential character of each group. You'd have to get the actual meaning of these terms from context.