"Professional pilots" is a redherring.
Passenger carriage, whether paid or not, is a responsibility.
The only difference in the passenger paying for the flight is that it is generally accepted that if somebody is paying, they have a greater expectation of safety. This is certainly true (and has led to a massive edifice of "safety" regulation and all the associated empire building to be created) but nobody expects to get killed as a passenger.
I have no problems with a solo pilot getting killed, because the State has no business dictating an individual's attitude to risk. Rock climbing, scuba diving, etc, is not regulated. For 2 reasons: (a) no 3rd party risk (a plane crashing on one's head is a massive emotional/institutional issue, exceedingly unlikely though it really is) and (b) no passengers to kill.