Under high voltage the current still follows the path of least resistance even when it looks like it does not. What people don't think about is that resistance is not a constant and under strong enough electric field dielectric materials (isolators if you will) can loose their propeties. Strong enough field can rip electrons from elements causing ionisation. Other things such as temperature, mechanical stress, radiation also affect different materials.
So what high voltage changes is making it harder to resist, but charge will still follow least resistance and aim to go for the nearest lest resistance material if such is available.
PS: I have studied all of this in a different language so I may have mixed up some of the terminology in English
Well, everything is a ~~dildo~~ conductor if you are ~~brave~~ high voltage enough.