But such a thing would attract them. Like rich people attract kidnappers.

Is there a faster way of becoming prime suspect? The kidnapping equivalent would be allowing random people to take out 'kidnap insurance' on you (with your agreement). If it so happens that you are kidnapped, it's pretty obvious which door the investigators will knock first.

Generally people who kidnap believe they can get away with it by never being in the frame as it were. Given that you'd be one of the prime suspects on motive alone in this case, it seems like a bet on being able to commit a "perfect" murder.

I don't think it's a likely occurrence

But this attracts the few who are.