Only if you’re literally running your own datacenters, which is in no way required for the majority of companies. Colo giants like Equinix already have the infrastructure in place, with a proven track record.
If you enable Multi-AZ for RDS, your bill doubles until you cancel. If you set up two servers in two DCs, your initial bill doubles from the CapEx, and then a very small percentage of your OpEx goes up every month for the hosting. You very, very quickly make this back compared to cloud.
It depends on how deep you want to go. Equinix for one (I'm sure others as well, but I'm most familiar with them) offers managed cross-DC fiber. You will probably need to manage the networking, to be fair, and I will readily admit that's not trivial.
I am referring to the layer 3 connectivity that Wireguard is running on top of. Depending on your use case and reliability and bandwidth requirements, routing everything over the “public” internet won’t cut it.
Not to mention setting up and maintaining your physical network as the number of physical hosts you’re running scales.
If you enable Multi-AZ for RDS, your bill doubles until you cancel. If you set up two servers in two DCs, your initial bill doubles from the CapEx, and then a very small percentage of your OpEx goes up every month for the hosting. You very, very quickly make this back compared to cloud.