At a previous job, the company had its critical IT infrastructure on their own data center. It was not in the IT industry, but the company was large and rich enough to justify two small data centers. It notably had batteries, diesel generators, 24/7 teams, and some advanced security (for valid reasons).

I agree that solving technical issues is very fun, and hosting services is usually easy, but having resilient infrastructure is costly and I simply don't like to be woken up at night to fix stuff while the company is bleeding money and customers.