Unsustainable customization vs. aggressive viruses

How is it possible that unsustainable customization exists, if it is unsustainable?

It is paradoxical why there are aggressive viruses that kill their hosts is short time, since this implies the death of all the virus present in the host. This is unsustainable. However, in a dynamic world where more reproduction (of the virus and of the hosts) speeds up mutations, this increases the chances of survival of descendants of the virus and of the host species, which have a sustainable relationship with each other.

In a dynamic world, unsustainable economic activities are an effective way of creating new sustainable economic activities. Despite its negative side-effects, the overall process may be worth it, since an activity is only sustainable with respect to a context, which changes unpredictably overtime.

For instance, the fossil fuel industry is unsustainable in its present form. But it made a decisive contribution against slavery, which was by itself ecologically sustainable but morally wrong. And it created an economy where solar energy was developed, which (likely) will severely diminish the relevance of fossil fuels in the economy. The earth is warming as a very negative side-effect.

Note that we are not rationalizing the damage created by the fossil fuel industry. We are comparing it with aggressive viruses which can be a very destructive force. However, it is crucial to understand that classifying fossil fuels as a "market failure" in a capitalist economy does not imply that its relevance in the economy will diminish in the future. We need to understand why fossil fuels could become so relevant, despite being unsustainable.