VPS, although more expensive than the shared server, gives your SaaS startup many benefits that makes it worthwhile paying more. Although both shared hosting and VPS involve sharing the server with other businesses, you get dedicated share of resources which you exclusively use for your business.
Your business will not be bogged down by the activities of other users in VPS. You will enjoy good speed and enhanced performance in comparison to what you experience in shared hosting.
your website is hosted in an exclusive rack away from the other websites that are sharing the server. This gives your business an additional layer of protection and privacy.
VPS gives you control over your server space. You have the liberty to scale your resources without affecting the other websites. You can install applications you want and reboot the server any number of times without disturbing the websites sharing the server with you. Shared hosting has several limitations like you cannot increase your resources. Your website will also become unavailable if the server crashes and security concerns are more in shared hosting.