I've found very few cases where "punting that over to a cloud provider" has been remotely cost effective for base load. It's gotten closer over the years, but the gap is still massive for all but some very specific types of workloads.
It's great for convenience, and it's great for managing without certain skillsets that may be hard to obtain, and it's great for temporary capacity, but it's not cheap.
It's not cheap to have any confidence of any uptime realistically at all. The thing is that most people either live without that guarantee, or just get lucky enough not to care. It becomes problematic if you've made promises to others about uptime that are built on a house of sand.
Unless your base load cloud costs are more than the cost of full time, ready at a moments notice, experienced ops people you don't get close to any guarantee of uptime by non-managed hosting. The salary cost alone of that is substantial, let alone hardware spread across multiple locations. My firm pays at least 7 figures a year on IT ops and don't come close to 99.9% uptime across everything.
It's great for convenience, and it's great for managing without certain skillsets that may be hard to obtain, and it's great for temporary capacity, but it's not cheap.