Yeah, they're lighter than air, so they do float to the outer atmosphere (as is ozone). It's actually pretty common for gasses to float that high. CFCs are only degraded by UV light, so they aren't degraded until they start getting close to the outer atmosphere, where UV is more intense. The reason why the hole isn't centered over a population are is because they are gasses that do not mix. Think about oil and water, even if you shake it them together, the oil droplets will eventually coalesce back into a single blob. Lastly, as odd as it may seem, the atmosphere has resonance frequencies that allow weather patterns to stay in a relatively fixed location, which is why it has stayed near the south pole for so long. Go look at the hexagonal storm at Saturn's pole, it's the same phenomenon. Any other holes that are formed would eventually make their way to the larger one and "merge".

Yeah, they're lighter than air, so they do float to the outer atmosphere (as is ozone). It's actually pretty common for gasses to float that high. CFCs are only degraded by UV light, so they aren't degraded until they start getting close to the outer atmosphere, where UV is more intense. The reason why the hole is centered over a population are is because they are gasses that do not mix. Think about oil and water, even if you shake it them together, the oil droplets will eventually coalesce back into a single blob. Lastly, as odd as it may seem, the atmosphere has resonance frequencies that allow weather patterns to stay in a relatively fixed location, which is why it has stayed near the south pole for so long. Go look at the hexagonal storm at Saturn's pole, it's the same phenomenon. Any other holes that are formed would eventually make their way to the larger one and "merge".