Yes. "Quantum computers will revolutionize computing by year 2100" is a claim I can take seriously. "Quantum computers will revolutionize computing real soon now" is a claim I am not taking seriously.
And yes, the 1950s AI researchers also boasted that it would take only months, what ended up taking many decades: https://en.wikipedia.org/wiki/Dartmouth_workshop
How much money should we putting into something with a time horizon longer than the working careers of everyone here?