Quantitative assessments typically employ a set of methods, principles, or rules for assessing risk based on the use of numbers This type of assessment most effectively supports cost-benefit analyses of alternative risk responses or courses of action.

Cloud platforms can be incredibly resilient. but single cloud assets are typically less resilient than in the case of traditional infrastructure. This is due to the inherently greater fragility of virtualized resources running in highly-complex environments.
Reference: CSA Security Guidelines V.4 (reproduced here for the educational purpose)

It is the characteristic of 0n-demand self-service that allows customers to scale their computer and/ or storage needs with little or no intervention from or prior communication with the provider

Remember, two key considerations when doing key management
1) Do not save it alongside data
2) Do not let cloud service provider manage the keys