I'm having a hard time understanding why investing later would be more expensive than investing now.

Unless you're taking into account the opportunity cost, I would expect the cost of investing in an electric infrastructure to be lower once the kinks have been worked out by early adopters.

On top of having a brand new set of expertise to shop for, the traditional automakers also will have to modify their existing factories. They'll have to do that eventually, but there might be some massive cost associated with adapting factories to the wrong tech.