Totally depends but speaking about institutional investors and corporation or with some individual billionaires then its been answered on the next comment or post next to this post on which majority of them would really be just storing it on exchangers which we know that its never been that recommendable on doing so but the fact that they are here just for the sake of profit then storing it up on exchangers would be the fastest way on executing some sell on the time that they would really be tending to scalp out some profits on their investment rather than on actively be transferring it out into their hardware or non custodial wallet
but of course not all would really be that so dumb on doing such action yet we know on whats the risks on storing up your assets on centralized platforms.

Whatever the things that they've been doing then its their choice and its impossible that they arent really that aware of the risks considering that these fellas are already that veteran on investment
world and with those security issues and concerns should really be that darn pretty basic for them and they are surely aware of that.