~Why will one posses such amount as an Individual?
They have that number of bitcoins first because they can afford to own it, and they do it because they see a future in it.
~Are there any consequences to this?
They can actually loose it all if things go sideways. Although I am certain that whales have other investments that are sustaining them in this bear season, it will hurt them to lose their crypto investment either to the market or to theft.