Some things that you buy for use in business may be deductible business expenses if you use them to earn taxable money.
Otherwise, stuff you buy (gold, cars, furniture, clothing) is never a tax deduction. It's just stuff you buy.
If in the future, you sell something for more than you paid for it, you have a gain that is usually taxable. And if you sell an investment for less than you paid for it, you usually have a deductible loss.
Bitcoin is treated like other investments like gold coins or stocks. Keep track of the price you pay now; if you sell in the future, you may have a taxable profit or a deductible loss, but only if you have the proof of what you paid.
