Helium supply is dwindling
That very well may be correct, but I find it hard to believe that we have a) exhausted the entire supply on our planet (yes - it may be more expensive to find more, but need finds a way) and my guess is that there are other gases that would do almost as well that are available to try. The air we breathe is not clean (even when filtered) and cleaning it better would also help. I understand that it is heavier than helium. Why not Hydrogen? It is even lighter and pretty plentiful. In a closed environment, it is not a fire hazard unless it gets too hot and we know how to lower the temperature sufficiently - we already do it for our CPUs and a closed circuit water cooling system is not that expensive and with more use will be even less expensive.
