All gun materials degrade (steel rusts) if not given proper care. Modern plastics should not be affected by normal gun cleaning materials, but people do try cleaners and solvents not made for guns, so no one can really say what they would affect.
I don't think modern gun makers really care much about investment, if any gun makers ever did. (The "made as a collectible" fad is recent, and usually the guns are poor investments.)
Did Sam Colt, in his little factory at Paterson, want to manufacture investments? I think he wanted to move product and make money and didn't give a hoot what happened to the guns after the money came in. Of course, not enough did, and that is another story.
Jim