Risk assessment - non-linear probability impact scale



Why an organization would use non-linear probability impact (0.05, 0.1, 0.2, 0.4, etc) scales for risk assessment ?

From the book, the explanation is  "the organization wishes to avoid high-impact threats or exploit high-impact opportunities even if they have relatively low probability".

However, i don't understand yet, please, any person can explain in other words?

Thanks in advance