You must not have read all my prior comments. Please go back and do so. The law is clear, and it doesn't matter whether SBD and SP are considered property or currencies, the tax effects are the same.
As I indicated in prior comments, if (for instance) you find a treasure of one-of-a-kind ancient artifacts (that is, property) in your back yard, you must must pay tax on the fair market value of that property as of the day you found it, and you must make a good faith effort (including hiring appraisers if necessary) to determine that fair market value. The property is taxed at its fair market value in the year you found it even if you never sell the property but instead just hold it. Furthermore, the value of the property is considered ordinary income and taxable at ordinary income rates. The fair market value on the day you found it then becomes your tax basis in the property.
If you do later sell the property, then your taxable gain (or loss) is determined by subtracting the sales proceeds from your tax basis (that is, from the fair market value on the day you found it). And, any gain or loss would then be a capital gain/loss.
Again, then tax treatment of found property is not even a tough question. It's black and white law. You'll find numerous examples here: https://www.google.com/search?q=if+I+find+treasure+is+it+taxable&rlz=1C9BKJA_enUS677US679&oq=if+I+find+treasure+is+it+taxable&aqs=chrome..69i57.4504j0j4&hl=en-US&sourceid=chrome-mobile&ie=UTF-8
So again, it doesn't matter whether SBD/SP is considered a currency or property, the tax treatment is the same.