The TU-144 was killed off by horrendous fuel consumption. Th erange was so short, if it took off from Moscow, it couldn't leave the country without refuelling.
The US took an example of the Tu-144 and put the best US engines available in it. It still wouldn't work. It looked like Concorde but it was a poor imitation. That's the danger of looking over someones shoulder but not understanding what you see.
Branson should have been allowed to take them over; but the politics killed them stone dead.
I live in hope that there will be one resurrected, like the Vulcan. It serves no purpose except to make peoples jaw drop when they see it in action.