The ladies are best for answering some of this, but like many of us they may find it uncomfortable talking about personal income.
I am not sure if you are quoting income of strippers or escorts/providers. But some quick calculations base on the OP...
Let's take the average of the claimed daily income:
($450 + $300)/2= $375 (average of her high/low numbers, weekly)
Weekly income:
$375 x 5 = $1875 (weekly)
Annual income:
$1875 x 50 = $93,750 (assumes a couple weeks 'vacation')
So, by your girl's numbers, she makes about $94,000 per year, before expenses.
Main expense for escorts is probably incall expense, say $10,000 ($800 x 12 months), and there are probably some website maintenance and advertising expenses, some photography, etc. Other expenses (gym membership, hair and nail and etc.) may be higher for providers compared to civilians and hence the additions properly calculated as expenses of the job, but I don't know. These will differ between strippers and escorts, for that matter, especially since strippers will not have incall expenses. Some one-time equipment expenses for escorts are toys, and there are ongoing 'minor' expenses such as condoms, lube, drinks for clients, even water, tissues, and laundry. Phone expenses for a second phone. Drivers for outcalls. I am sure I forget something. Strippers will not have many of these expenses. Then again, strippers may need more clothing and shoes.
Car payments occupy everyone, as do phone bills for the 'civilian' phone, house payments or rent, etc. These are not expenses attributable to sex work, as everyone bears such expenses. Neither are drugs, for that matter, although there may be a correlation between drug use and choice of employment, and it may differ between strippers and escorts. I don't have any data on those issues, nor would I want to include drugs as a necessary cost of being a stripper or an escort even if they were more likely to use drugs.
If your nightly data is for escorts, I'd say annual income is about $84,000 net (at $375/day), a good income, above average surely, but not a level at which one is getting super rich. If the numbers you quote is for strippers, then $94,000 net, again a nice(r) income, but not one that will make you rich. Further, these numbers are pre-tax. I am not sure that escorts and strippers are not paying taxes. More than one has told me they do pay taxes, but of course I do not know if that is true, nor if they pay tax on all their income.
A related issue is that the income may require a full-time job for strippers, whereas escorts may be able to maintain at least a part-time civilain job and thereby earn additional income. This is a bit besides the point, and in any case I don't have any data.
You provide information on daily income from one girl. If a stripper, I assume that it is the daily income and not easily augmented by additional work as a stripper, but I don't know if that is a good assumption. If an escort, some here will undoubtedly argue that she could see more clients and double her income. While this is hypothetically possible, I am not sure it is really all that easy. In particular, I think she would have to lower hourly prices to attract twice as many clients as she is currently able to attract, and if prices need to be lowered then doubling her clients would not double her income. Further, to the extent that doubling clients lowered the quality of the experience for all clients (and I suspect this is true but certainly I don't know for sure) then doubling clients might well have a negative impact on repeat clients and hence negatively impact future income.
So, what is "all that money"?
There are many unknowns here. This probably requires an academic study -- I'll start preparing the relevant NSF proposal. I'm thinking I should propose myself for in-person interviews with a select group of courtesans, in order to get background information and a good feel for the data.