Hardware

Most HW startups fail because they never get the SW story right.

At the end of the day, hardware is used to run software. So unless you're having access to a large software library from the get go (by accelerating a known entity or architecture), or you truly have a fantastic value proposition in terms of being orders of magnitude faster than the established competition and with a solid roadmap in terms of HW and SW. The best most HW startups can hope for is an exit plan where their IP is bought by a bigger player.

HW people some time miss the boat that if something is 2x as fast, but it takes 2x as long to develop for, you're not giving that much in terms of leadership window for your customers. So they'll remain with the known entity, even if it's less efficient or performant, on paper.