The market for hitmen is thin

 The NYT has the story (but it isn't much of a story, the 'experts' don't know much...)

Was Brian Thompson’s Killer a Hit Man? Unlikely, Experts Say.
The murder of Brian Thompson did not appear to have been committed by a coldly calculating professional, according to people who study criminal behavior.   By Annie Correal

"None of this looks like the work of a professional, the experts said. (Assassinations occur but are usually ordered by governments or criminal groups like drug cartels, and rarely leave behind much evidence, they said.)"