I think demanding over 40% tax on a trivially worldwide transferable, hard to track, easy to secretly manufacture commodity is exactly the best way to create black market.
The official line is that credit and debit cards have high transaction fees, and that's true (especially for very low and very high prices), but cash isn't free to accept (security, counting, counterfeit risk, etc.), and yet service industries universally prefer cash over any other payment method. Why? Tax fraud.
if it is _long_ _term_ capital gains. short term gains are taxed at the same rate as regular income.
It was recently raised to 20% for people in the highest income tax bracket. AMT of 28% may be used instead in certain circumstances.
You'd probably have to depreciate equipment rather than deducting it, unless it has an expected useful life under a year or hits some de minimis threshold. (The IRS rule on this one is really wonky. Suffice it to say that most Bitcoin miners have to depreciate not deduct.)
(b) Useful life. For the purpose of section 167 the estimated useful life of an asset is not necessarily the useful life inherent in the asset but is the period over which the asset may reasonably be expected to be useful to the taxpayer in his trade or business or in the production of his income. This period shall be determined by reference to his experience with similar property taking into account present conditions and probable future developments. Some of the factors to be considered in determining this period are (1) wear and tear and decay or decline from natural causes, (2) the normal progress of the art, economic changes, inventions, and current developments within the industry and the taxpayer's trade or business, (3) the climatic and other local conditions peculiar to the taxpayer's trade or business, and (4) the taxpayer's policy as to repairs, renewals, and replacements. Salvage value is not a factor for the purpose of determining useful life. If the taxpayer's experience is inadequate, the general experience in the industry may be used until such time as the taxpayer's own experience forms an adequate basis for making the determination. The estimated remaining useful life may be subject to modification by reason of conditions known to exist at the end of the taxable year and shall be redetermined when necessary regardless of the method of computing depreciation. However, estimated remaining useful life shall be redetermined only when the change in the useful life is significant and there is a clear and convincing basis for the redetermination.