Giving the customer direct ownership of their CRM database is a feature, not a bug. They will benefit from a CRM development team who has dedicated experience and expertise in CRM, plus they'll benefit from the feature and security requests of the other CRM customers. And it will make them less dependent on you, specifically. Which, from the client's perspective, is a good thing.
Edit to add: what's more likely, that Salesforce goes down, or that you are unavailable for some reason?
https://en.wikipedia.org/wiki/Category:CRM_software_companie...
Giving the customer direct ownership of their CRM database is a feature, not a bug. They will benefit from a CRM development team who has dedicated experience and expertise in CRM, plus they'll benefit from the feature and security requests of the other CRM customers. And it will make them less dependent on you, specifically. Which, from the client's perspective, is a good thing.
Edit to add: what's more likely, that Salesforce goes down, or that you are unavailable for some reason?