If you are not already familiar with Linux system administration, you will need to devote a great deal of time to familiarizing yourself with all of the applications you're using and the CentOS operating system - you could pay someone else to set up your VPS for you, but that wouldn't help down the road when you need to update software and resolve administrative issues... (if you're not sure, go with a managed service)
Similarly, in a real dedicated server, you will pay for the entire server that is not shared with anyone else. You will get complete control over all services. Unfortunately, it is also the most expensive hosting option and needs some technical expertise to manage. It is commonly used by those who have websites with specific scenarios, most commonly extremely high traffic and tight security requirements.
I was running a small private weather website in AWS and the satellite images got "picked up" by a news website and they regularly use them during major weather evenings. AWS' 12c per GB of outbound network traffic made things expensive and VPSServer makes this a lot more manageable and has excellent data volumes included with the price of the VPS. I also get many more CPUs for the price compared to AWS, so I am a happy customer.
WHM's Backup Configuration section is one of the most powerful and vital tools for an administrator of multiple sites. It allows you to manage each of your individual cPanel backups separately, giving you the choice of backup cadence (daily, weekly, monthly and manually) and location. Preserving your clients business-critical files, data and site content is of the utmost importance. Work with your clients on implementing a backup schedule and location that is appropriate for their site(s) and make sure they have the peace of mind that their data and site material are safe.
With unmanaged VPS hosting, the cost is also much cheaper. It is not uncommon to find $10 unmanaged VPS plans because the web host does not have to pay for a cPanel or Plesk license and are able to minimize costs. Also, since the web host does not provide software and account support for an unmanaged VPS, the host also saves money on customer support. In the end, you'll have VPS hosting that is typically $20-30 cheaper than a managed VPS solution.
The force driving server virtualization is similar to that which led to the development of time-sharing and multiprogramming in the past. Although the resources are still shared, as under the time-sharing model, virtualization provides a higher level of security, dependent on the type of virtualization used, as the individual virtual servers are mostly isolated from each other and may run their own full-fledged operating system which can be independently rebooted as a virtual instance.