It appears this particular balloon was traveling at 60000 feet altitude. The flight ceiling of an F-22 is 50000 (according to the internet, although the actual number is very likely classified). If that's correct, then shooting a balloon from 10000 feet below with a machine gun is not easy. Even if you put some holes in it, such a balloon is not going to simply pop like a party balloon. It very likely does not have a pressure differential between the inside and the outside, so the holes will simply allow the air to mix slowly (very slowly) with the lifting gas inside (hydrogen or helium). It will probably take days or weeks before the balloon goes down.

The effective range of the F-22's Vulcan Cannon is 2000 feet - That's where you expect about a quarter of the shots to hit... When you're talking about a fighter-jet sized target. The bullets will easily travel, still at kill velocity, well beyond that. I have no doubts that for a slow moving target such as a balloon, they can spray and pray, and pop it every time.

You might be right. On the other hand, today they used a missile. Such a missile costs about $200k, while a Vulcan round is under $20 (collectors can buy one round for $20, see [1], the military can probably buy in bulk for much less).

Maybe they just wanted to show off. But maybe it's just not that easy to take down a high flying balloon with unguided munitions.

[1] https://www.gunbroker.com/item/968543844

My understanding as a layman is that we cannot shoot objects at altitudes 60,000ft+ with machine guns. We need fighter jets equipped with specialized missiles, or ground-based SAMs, that are very expensive, and have some limitation on their range.