I admits that it's necessary to advocate for conducive societies where everyone could enjoy the dividends of their struggles freely without getting illegally extorted especially in the world of this decentralized blockchain, users most interesting atmospheres is meant to be driven by financial freedom (where safety of values and identification of users remains anonymous) but the blockchain has become hostile where criminals now targets ones who owns bitcoin and even those who owns Bitcoin could not even maintain a private identification of themselves.
However, on this one of the story about the bitcoin investor gotten kidnapped could be a result of the kidnapper just being a thief of stealing from people and not likely that he was just interested of his Bitcoin.
I think since he's aware that the guy invests on Bitcoin, he believes that's the only form the guy can pay for the ransom. So likely, he might be demanding some other sort of values like fiats from other of his victims.