Large Investors in Btc in USA last year now have to pay 40% tax and are selling off btc to cover the Bill
Taxes for 2017 were due by April -- 8 months ago. In many cases, estimated tax payments were due earlier than that. What you're saying may have applied to the first few months of this year, but not now. This year was a lot less profitable than 2017, so there's probably a lot less sell pressure from people covering tax liabilities now.
Also, 40% used to be the
maximum tax rate on capital gains. For 2018, short-term capital gains are taxed at the normal income tax rate (0-37%). Long-term capital gains are taxed at 0-20%.