What you're describing isn't very realistic, since nobody would willingly choose the most expensive option(s) for transfer -- and CDNs aren't even particularly useful for live video, as the minimal latency increase of using a single location is easily counteracted with larger buffers, all of which is already baked in to the protocols.

Here's some counterpoint math including revenue, using even higher bitrates across a couple cheap load-balanced 4Gbps VPSs. For simplicity, I'll use a single average stream.

Transfer: 300 avg. viewers * 6 hours * 5mbps = 4TB @ $0.01/GB = $40

Revenue: 5,000 total views * 0.01 conversion * ($5 avg. contribution - processing) = $228

That's a $188 margin self-hosted versus approximately $120 via Twitch mechanisms. Presuming 5 streams per week, Twitch is taking a $17,000/year commission. Twitch does provide some other functionality and very minimal discovery, but if you already have a dedicated audience, then self-hosting absolutely makes sense for any sized streamer, especially considering that you're not limited to streaming to only one platform.