As a car enthusiast, I can think of a good one, the Ford Nucleon.
During the 1950s and 1960s, there was considerable interest in nuclear power and its potential applications. This led to the idea of using nuclear energy to propel cars. The concept behind a nuclear car was to utilize a small nuclear reactor to generate steam, which would then power the vehicle's engine.
Of course back in those days, this was extremely futurustic and some at the time thought this would be a game changer, but ultimately, the safety aspect was one of the biggest reasons why this idea was dropped, and I probably don't have to explain why it may not have considered to be safe, I mean, it was using nuclear power, so even if the engineers tried to make it as safe as possible, IF something went wrong, it would have been catastrophic.
Ever since then, the interests in the automotive sector has shifted to Electric and Hydrogen.
Still, a very intriguing concept car and idea.
Outside cars, you have blimps, and I personally believe if we tried to make something like a hindenburg today with existing technology, we might have been a lot more successful than back then (as it goes way back to 1930s), there are still some blimps used occasionally, I also don't believe those use hydrogen(?), but they are not the "game changer in air travel" it was once seen as, although we can't rule out a comeback.
What about you guys?
Not considering vaporware or failed products (e.g. Eolo car):
The Esperanto language. (Yes, I'm old)
NFTs.
Blockchain. Yes, it has its use, but it's not the pervasive, all-use game changer it was claimed to be.
Sony Betamax. Pity because it was better than VHS.
New Coke. Nuff said.
What did Beta do better than VHS? It's a load of hype from Sony that Beta was better - magnetic tape was magnetic tape and compare the picture side by side (which most homes couldn't because beta machines cost 2x as much as VHS). There is no difference except buyer's denial they paid more for the less runtime (Beta has an hour long format while VHS was 2 hours).
I knew what video that was going to be before I even clicked it. Technology Connections is awesome.
Yeah but sony made VHS also... It was their Alpha release. They intended to wait a bit and release beta, which has already been developed shortly after vhs hit stores. What they didn't expect was to be copied by a competitor before that happened, effectively making VHS a standard. As you say, magnetic tape is magnetic tape and they thought their first attempt would quietly fade into history when they put out version 2. Instead it was a desperate marketing war for relevance.
Esperanto is over 100 years old, when was it poised to be the next big thing?
70s and 80s.
People like to claim that blockchain will sold world hunger but really it's just a database system so unless your problem is database related blockchain isn't going to fix it.
The problem they tried to use blockchain to fix was I don't like the government controlling what I do with the money and knowing I commit crimes. Which isn't really a database issue it's a getting caught issue. If you don't get caught you don't need to use bitcoin and you don't need to use blockchain.
Blockchain is a massive innovation for certain industries. Tragically at this point when I read it, I default assume it's a buzzword techno babble selling point for a system that absolutely doesn't need it.