As everything, a big “it depends”. Each viewer will eat more bandwidth, but you control the compression and qualities. For me, I have an unlimited fiber uplink, so it’s quite easy for me to self host. If someone were more bandwidth constrained, then hosting it on a cloud that then has much more egress may help - at a cost of course, but then your own personal internet would only have the one outgoing stream. Finding a provider that has super cheap egress traffic would probably help

If you have a data cap… well… not a lot you can do.