On the software side... depending on your business model, you can factor in a lot of the cost structures into your structure. Especially for say B2B arrangements.

Cloud integrations, for example, allow you to simply use a different database instance altogether per customer, while you can share services that utilize a given db connection. But actually setting up and managing that type of database infrastructure yourself may be much more resource intensive from a head count perspective.

I mention this, because having completely separate databases is an abstraction that cloud operations have already solved... while you can choose other options, such as more complex data models to otherwise isolate or share resources how does this complexity affect your services down-stream and the overall data complexities across one or all clients.

Harder still, if your data/service is centered around b2b clients of yours that have direct consumer interactions... then what if the industry is health or finance where there are even more legal concerns. Figuring a minimal (off the top) cost of each client of yours and scaling to the number of users under them isn't too hard to consider if you're using a mix of cloud services in concert with your own systems/services.

So yeah.. there's definitely considerations in either direction.