On the upside, internal storage devices are cheaper than their external counterparts. The main reason for this is because internal storage devices do not need to have durable and aesthetically pleasing casings since these devices will just sit inside your PCs. Aside from its cheaper price, internal storage devices don't need to be charged or plug-in to a power source to run. Since it sits on your PCs, its power comes your PCs power supply. Another advantage of using internal storage devices is that it is free from external threats that may damage it. Your PC's casings would be more than enough to protect the internal device as well as the data tha reside in it.