IBM and Google have invested massively because someone there thought that it actually would be useful. But that hasn't happened yet and to be honest it doesn't look like that will change any time soon.
Inregards to Neural Networks, they were pretty much a complete dead end until computing power increased enough to make them viable. In that case an external technology had to come along to make it work.
Plus what is the near future anyway? If big tech companies spend 2 billion a year on quantum computing for the next 25 years (which is how long it took to get from Geoffrey Hinton's book to fully commercial applications) that's 50 billion. OpenAI + Anthropic are valued at >100 billion. Even if they just broke even doesn't that seem worth it to control the next generation of computing?
And idk other than this, robotics (self driving, manufacturing, agriculture) and AGI what else is there to bet on for the coming decades?
When computers first began development during WW2, they were a response to immediate demands for particular functionality from many technical areas. Quantum computing seems to go the exact opposite route, first of building up an (admittedly very interesting) technology and then later figuring out if there actually is anything useful to do with it. The connection to AI is particularly interesting, because it seems to be built entirely out of a combination of two buzzwords.