Concerning the comment about using another inert gas, I would say that the atomic weight of the molecules is probably a determining issue, which would make helm the most useful inert gas for the filling of hard drives.

Concerning the limited amounts of available helium, I suspect that hydrogen would be also effective in this use, and it is readily available, and at the small amounts in a hard drive, it would not be much of a fire or explosion risk.

Concerning the limited amounts of helium, I suspect the amounts to be used in a hard drive case is very small compared to a balloon, so just stop using it in balloons and there will be plenty available. and the market place would much such an allocation, should the availability of helium become an issue.