A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it.

Getting stuck on certain ideas might be just a side effect of the aging/degrading brain and not necessarily depend on the years lived with an idea. Of course, if you live years with confirmation bias and sunk costs et al, you might have a lot of accumulated bias to counter. I think sunk costs is the most important psychological explanation for this phenomenom if biology is out, but might not make much sense to an immortal.