Can we crowd fund a guillotine or two?
Why? What's the point of shooting the person who has no say in what money he is given. The sovereign fund is decided on and controlled by Parliament. Cameron introduced the current arrangements.
I agree that this has a bad optic, but you also have to look at what the sovereign fund is for. Charles isn't buying Lamborgini's and super yachts. Most of the money goes to repairing / refurbishing our historic palaces and the remainder on public functions, Royal visits etc that the King is expected to host.
A better question would be about personal profits from the Duchy of Cornwall etc, although again, it would be better to look at how and where the money is spent and see if it could be better directed.