They think a breakthrough leading to a cheap battery with double the energy density is around the corner, and they don't want to bet the farm on the current state of the art. They think Tesla will be left holding the bag, while they (the incumbents) will rush to convert all their manufacturing in short order to electrics once that mythical technology is available. They think they will be able to scale fast because they have the money to invest in a sure thing (but it must really be a sure thing).
They think that is the only way for them to switch to electrics: in a sudden, sweeping transformation (a few years at the most). They are afraid to invest in the meantime because they can't get to profitable volume quickly with today's electric tech. Any serious push into EVs now, without the guaranteed ability to swim all the way to the other side, would cannibalize their ICE money-makers, killing the company.
And I think they are right. They are screwed, unless that miracle breakthrough battery materializes.