Years? If you have some friends over for cocktails a 12 oz bottle of simple syrup would easily go in an evening. You’re looking at about 12 servings there. (Or fewer if you like your drinks particularly sweet.)
Apparently, according to Serious Eats, I’m wrong. Up to a 2:1 sugar:water solution of will dissolve fine without heat. You just need to wait about 45 minutes and shake/stir it midway.