I also have colleagues who promise small concrete incremental deliverables in predictable timelines. They rarely talk concretely about the big end goal pie in the sky’s timeline, but generally deliver the big thing sooner anyways.
The answer isn’t making reasonable estimates of an inestimable thing, it’s providing reasonable estimates for the reasonably estimable pieces. Instead of “we’ll have ultra mega science in three to five years!” it’s, “we’ll have this specific piece of the stack built by 2022 and we hope it’ll enable these other slightly less concrete things towards ultra mega science.”
There is a reason why legally Autopilot/FSD is a driver-assist system, but for marketing purposes robotaxis are just around the corner.
There is a fine line between 'overly optimistic' and misleading, and more often than not, Elon crosses the line.
See https://elonmusk.today/ for an overview (if a bit biased).
My point isn't that these companies don't get there, it's that they take much, much, much longer than estimated.
Note that they have done zero work on building a anything other than the rocket body to get there. Making the interior volume habitable for 2 years of interplanetary travel is going to be non-trivial.
Reasonable estimates like what ? If your company works on something that has never been done before there is not much data at hand to make good estimates is it ?