Perfect. Pleading for leniency is the next step. See, the same argument is used for God. "You know we can never prove it, so you have to cut us some slack in what is required to convince." And that is not an argument that favours believers. That being said, it's also not true. One of these things could crash, or or drop an alien cellphone, or land in front of a news team, or land on the Whitehouse lawn. There are innumerable ways that proof could come - like with every other advancement in human knowledge. The fact that they don't is not the skeptic's problem; it's yours.