Many are gambles, many are funded by those who know buzzwords but not the actual market or viability. Once that funding runs out, often the buzzword has moved on to something new so no more funding can be gained. You have to find a way to make money without funding in that period. The key issue is trying to grow too fast with too few solutions. If you can solve a problem for people then that is giving you a good chance of survival.
A lot of startups get built around hype instead of a real problem. When the buzzword fades and the funding dries up, the company suddenly has to stand on its own legs, and many can’t.
Growing fast without a solid solution underneath is a dangerous combo. If you’re not solving a real, painful problem for someone, no amount of funding or storytelling will save you.