For your first two, economics were the issue. The aircraft weren't economically viable, as they were limited to only a handful of routes and were very expensive to fly.

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On a deeper level, there's a lot of politics and engineering to the relative failure of the Concorde and Tu-144. Interest in supersonic transports (SST) began in the 1950s as advances in aerospace technology showed that large, long-range supersonic aircraft were technically viable. On both sides of the Atlantic, designs were being developed for SSTs of various sizes and speeds. Britain had been openly sponsoring SST development through the 1950s, Boeing had their own internal programs, and Lockheed, North American and Convair all had preliminary studies for SST development. In 1962, Britain and France had begun preliminary talks to coordinate their SST efforts - combining their Bristol 223 and Sud Super Caravelle, respectively. America soon followed suit, with the Kennedy Administration and Congress sponsoring American SST development spurred by fears of European SSTs dominating the American aviation market. Around the same time, the Soviets would announce their own SST program around the same time.

The American and European SST programs would take on a markedly different character. The Americans were pushing for an ambitious project with a cruising speed of Mach 3 and capacity of around 270 passengers, with plans calling for an eventual fleet of 500 SSTs to be operating for commercial carriers in the US. The European proposals were a bit more reasonable - original Sud and Bristol proposals came in at under 100 passengers, and the resulting Concorde maxed out at 120 passengers in a high-density layout and would cruise at "only" Mach 2. Where the Americans were hoping for a large, long-range aircraft, the Europeans went with an intermediate-ranged aircraft.

And that would pan out in the Europeans' favor. The Boeing 2707-200 design that won the US government contract initially was almost an absurdly complex plane, even discounting the ambitious interior amenities. It was well over 300 feet long, which would make it the longest aircraft ever made. It was to have swing-wings with a complex system of slats and flaps to allow it to takeoff and land in a reasonable distance, and the placement engines in the tail meant that a special system had to be devised to route air from the top of the wing to the inboard engine intakes when the landing gear was down. The nose was another issue - it was so long that the normal drooping nose of every other SST proposal wasn't enough and a second joint had to be added to keep the drooped nose from hitting the ground. Not surprisingly, this design proved impractical, and Boeing ultimately had to scrap this design, as they'd found that the extremely long aircraft was going to suffer from unacceptable amounts of flexing in flight. Boeing was allowed to scrap their initial design (though not without much protest from Lockheed, which had a more conservative design that was more in line with what Boeing ultimately redesigned to), but by this point it was 1968 and the hype over SSTs was starting to wane as the realities of environmental damage, noise, and, most importantly, cost overruns came into play. The project soldiered on long enough for Boeing to make a full-scale markup of their new design, but in 1971, the American SST was cancelled.

Ultimately, those same (non-economic) arguments that undermined Boeing's SST efforts would come in handy in the years that followed. Boeing joined the forces lobbying to ban supersonic flight over the US mainland, and, with no American SST to protect, Congress would ban such flights soon after they cancelled the Boeing SST. That was a heavy blow to the potential SST market, as it eliminated a major source of air travel. Compounding the impact was the sheer economics of an SST - due to the higher per-hour cost of operating an SST, the aircraft are only really viable at longer ranges where the time savings versus subsonic aircraft are significant enough to justify these added costs. With the intermediate size the Europeans had opted for with the Concorde, the new restrictions eliminated a huge number of viable routes and really only left a handful of transatlantic routes. Costs had meanwhile skyrocketed, and, as the 1970s came, oil prices began to rise as well, undercutting the entire economic equations that justified SST development in the first place. Orders from almost all of the original 16 airlines that had placed orders were cancelled, and when the Concorde finally entered service in 1976, only Air France and British Airways would operate it. Even then, production was very limited due to the cost - only 20 Concordes (including prototypes) were ever made.

Over the course of the Concorde's career, it ended up being more of a novelty than a viable economic platform. Tickets were very expensive, and, contrary to expectations, passengers weren't as keen to pay more for a shorter flight as projected. Demand remained low throughout the entire career, and routes were constantly subject to change due to local restrictions owing to the aircraft's extreme noise - even when flying subsonic. By the turn of the millenium, the Concorde's already iffy economics were now being undercut by rising maintenance costs. The final blows came in the shape of the post-9/11 air travel slump and the crash soon after, leading to both Air France and British Airways to retire the aircraft in 2003.

As underwhelming as that may seem, it's still significantly better than the Tu-144's career. If the Concorde was bordering on a white elephant, the Tu-144 was purely a vanity project. It was subject to similar restrictions over populated areas due to noise, limiting it to only a single route - Moscow to Almaty. The design was considerably less refined than the Concorde and was hampered by the Soviet Union's chronic issues with staying up to par with Western engine technology, so mechanical failures were extremely common. Even worse, the Tu-144's engines were unable to provide enough thrust to maintain supersonic flight without relying on afterburners (as opposed to the Concorde, which only relied on afterburners for takeoff), so cruising flight was extremely fuel-hungry. Between the high costs, limited practical use, and alarmingly common mechanical failures, the Soviets would retire the Tu-144 after just 55 commercial flights in 1978.