Why would anyone ever risk $1 at that marginal rate? If they are wrong, they lose the $1. If they are right, they make $0.30. That's a horrible risk : reward proposition. In some states and income tax brackets, the marginal rate for many is already at 50%. At that point, the only option left for ambitious people who want to keep more of what they earn is to leave...as happened with France. Of course, then they will raise the exit tax (and lower the eligibility threshold).
I've often predicted that bitcoin is eventually headed to $0. But if we do see a wealth tax as Elizabeth Warren and other politicians have been asking for, then I'd have to reconsider my bitcoin thesis as tax evasion becomes much more enticing for many.