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He doesn't wish to have Bitcoin. Instead he wishes to forcefully get and scam someone out of their hard-earned coin (maybe) to the extent of killing. There's a clear difference....
The story looks a little vague anyway but there might have been something between them earlier before it led to that.
I agree with what you mentioned. BTC is somehow irrelevant here because it could be any money that the person wanted. It just so happened that the victim had cryptocurrencies which represented his wealth. If he had any other wealth, the thief would probably exhausted all the means to get that money to his own benefit.
Unfortunately, there are some news regarding the involvement of cryptocurrencies to various criminal activities. More people are becoming aware of the opportunities that crypto bring as they started targeting individuals who possess it.
With these recent criminal activities, I just hope that the government would provide the necessary implementation and execution of laws against these scammers and criminals.