Consider the analogy of landscaping for your home. Some people take the approach of doing it all themselves, owning all the equipment (lawn mowers, trimmers, etc.), and enjoy personally putting in the effort themselves. Others don’t like the work, or don’t have the time, and instead choose to engage a third-party service to do it for them. In this case, there is no obvious right or wrong solution. However, in the case of work and business, the consideration between the DIY approach and engaging a service is different from a personal hobby or effort.
One practical definition of Cloud Services: where there is a computing need — e.g., servers, disk storage, web hosting — instead of fulfilling this by buying the servers, disks, and setting it up and maintaining it on-premise, you would engage a third-party to address the need instead, with hardware and software managed by them. In many cases, researchers, departments, local IT staff, and others may have a technical need and funds to support the need, but do not have the time and/or the expertise to take on the additional effort required for traditional, on-premise solutions.