Often times companies move because their organization doesn't deliver, and the hope is a cloud company will do a better job of it.

If you have a great team, I firmly believe hosting yourself is far, far, far less expensive.

If you have a terrible team, then cloud (hosting) is less expensive. Even if it was exactly the same cost, you're gaining by not having to have a staff to run it, and the costs of managing them, etc etc.

Most places don't have great teams. Insert random corporation here likely has a team that is a mess for whatever reasons happen in large companies.

In that case, the Cloud makes a ton of sense for them. They've already screwed up their own organization in some way, and this is a large reset button on the whole thing.

That's worth a ton in itself.