Why does MarketPlaceService have some many loop holes?

local assetId = script.Parent.MarketID.Value
script.Parent.MouseButton1Down:connect(function()
Game:GetService("MarketplaceService"):PromptPurchase(game.Players.LocalPlayer, assetId, false, 2)
end)

I have this code inside of the gui to make it be able to buy something but it does not work for some reason.

You need to use a LocalScript for this.