@OP you are not thinking about this in the right way.
Just because its called a bit"coin" does mean it's money.
You can't use it to pay taxes.
It is not recognized as a currency by the BIS
Almost nobody accepts it in payment. Try "paying" your accountant or tax adviser in bit"coins".
By the way, I'm also eating some chocolate "money" as I type this.
BTC are simply a virtual good. Like a lot of people you seem terrified of the law and or government...this should tell you something about the system you live in.
Very true.
If you held a World of Warcraft character that "appreciated" from $200 to $600 dollar, would you have to declare this? Don't tell me its "illegal" to sell your Warcraft account....it IS however against Blizzards "Terms of Service". Other online games *allow* trading of virtual goods. People in EVE online sell Pilot Extension licenses all the time, and this is endorsed by the Company (CCP). The value of Pilot Extension License changes all the time....you DONT have to declare a "capital gain" in your pretend on-line spaceship to the government.
Under US law, yeah, actually you do (unless the government has seen fit to explicitly exclude virtual goods).
26 CFR 1.61:
Gross income means all income from whatever source derived, unless excluded by law. Gross income includes income realized in any form, whether in money, property, or services. Income may be realized, therefore, in the form of services, meals, accommodations, stock, or other property, as well as in cash. Section 61 lists the more common items of gross income for purposes of illustration. For purposes of further illustration, §1.6114 mentions several miscellaneous items of gross income not listed specifically in section 61. Gross income, however, is not limited to the items so enumerated.
Not commenting on the morality, etc. Just stating the view of the folks who happen to have more guns than you.