There is no scenario where the government doesn't know it exist and the Bitcoin is useful in any way to your life. If you ever use it for any thing there's a bright line directly to you. The silk road guy was taken down for screwing up one time years before he even started the website. Maybe a criminal organization that forces their grand children into it can potentially hide a wallet.
The silk road guy pretty much had a government department trying to shut him down. They don't have the resources to do that for the average individual.