I'm seeing a great deal of misunderstanding about what is and isn't available in the cloud. And when I refer to "the cloud", I mean the big players like Azure, AWS, GCP, etc.
* You never lose control of your data, only of the hardware and physical environment in which it sits. That becomes the responsibility of the cloud provider, who contractually provide SLA guarantees for their infrastructure. On top of that, their security is best-of-breed and very few firms can compete with them on that level.
* They can appear expensive, yes - but, you need to take into account a few factors that result in hidden costs of on-prem units. Electricity, cooling, real estate, maintenance staff, support contracts, hosting software, all these combine to make a normal box-in-the-closet rather expensive. Top that off with the cloud monthlies going onto the "Operating Expense" line in your accountant's ledger rather than "Capital Expense". That ends up with some significant tax advantages.
* Also on the note of the expense side - flexibility to scale in and out as needed. For example, let's say your favorite number-cruncher generally has a hefty workload during the last three days of the month for payroll or sales invoicing, etc. You can schedule your server to up-scale its CPU capacity during those three days, and back down every other day of the month. And then you only pay for what you use. By the same token, if you find your company is suddenly getting slammed with too much traffic, you spin up a few new web servers in a matter of minutes.
* Many storage costs are only paid on egress of data from the cloud.
* The major players among the hyperscalars offer geographical isolation of data. If I get a storage account in Western Europe on Azure, for instance, I am guaranteed that data isn't going to leave the region.
There's a lot more to it, and it's definitely worth reviewing in more detail.