I can't figure out which part of this you object to. You seem to accept all the numbers, but continue to argue about the shape of the box they're presented in.
How delightfully condescending of you. Yes, I didn't realize that the 5% number came from you, that hardly makes me "confused". Taking that into light, it's not obvious to me how a very rough back of the envelop projection is significantly more ridiculous than a number pulled out of thin air. My whole problem is that you called it ridiculous when it was clearly meant to be a rough order of magnitude projection. You can't really criticize a number pulled out of the air, because it goes without any attempt at justification. But a back of the envelop calculation can be improved in a piece-wise fashion to hone in on a better result. So any attempt to model a phenomenon (as long as it doesn't come with unjustified claims of precision and certainty) is an improvement over a number pulled out of the air. But that process is short circuited when people just dismiss the projection out of hand as you did. This is why I appealed for an improvement in my first comment. It's really easy to shit on someone else's effort, but it is completely unproductive. If you see a problem, then fix it. Then you're adding to the conversation, rather than just shitting on a little bit of effort someone put out there.