Why are scientists concerned about species loss even though extinction is a natural process?

The extinction of species is a natural process. Over the time, multiple species have become extinct. The process of natural selection ensures that only the most adapted species continue on the Earth. However, when the extinction rate increases then it causes a disbalance. The extinction of one species will cause a sudden rise in the species of its prey and this will cause a disruption. Therefore, the scientists are worried about the loss due to extinction even though it is natural.