I agree with you that a 'house dancer' with a $5000 first time boob job with right out of the catalog sized breast implants can definitely pay them off within a year. I also totally agree that, in the right city with the right clientele, it's not difficult for a 'house dancer' to gross $1500 a week working 40 hours in the same club located close to her home. This makes perfect sense from a business standpoint - the investment was reasonable and the expenses are low.
But consider a girl who is seeking HUGE implants. To get there, she first has to do the starter set of catalog sized implants (like 600cc) for $5000. Then she has to do a larger set of custom made US implants (like 1200cc) for probably $10,000. Then she is finally ready to do an even larger set of custom made european implants (like 2500cc) in the $25,000 ballpark. To get to the really HUGE size range (like 4000cc), she'll probably have to do a second larger set of custom made european implants with another $25,000 price tag. An alternative is to go with a set of custom made european implants which are adjustable, but these must eventually be replaced with permanent implants once the final size is achieved resulting in about the same overall cost.
As you can see, the simple $5000 one time investment for house dancers doesn't compare at all to the cost of getting to HUGE sizes, which easily runs 10+ times higher when all is said and done. In fact, for house dancers graduating to the second step (1200cc size range), this can actually hurt her 'house dancer' earnings significantly since she's now big enough to spook many regular club customers who will think that G cups are freaky, but not big enough to receive serious attention in the big boob world.
It's also necessary to consider the travel and accomodation expenses which go along with featuring. Even though the girl may be receiving an extra feature fee, it's not uncommon at all for that feature fee to not even cover air fare, hotel and meal costs in an expensive city. Same goes with web servers. It's not uncommon for one hacker attack to rack up bandwidth bills that totally consume the entire month's membership fees of a model's pay website.
This was my whole point, that with today's business conditions it's really questionable whether or not it's worth the major investment and extra risks for a house dancer to consider trying to achieve HUGE boob status. With $50,000+ invested in the HUGE boobs, plus $1000+ per week in travel and accomodation expenses that a house dancer doesn't face, we're probably talking a $180,000 annual income for a feature to actually come out ahead vs simply staying a house dancer with catalog sized implants and avoiding the large implant investment and travel expenses. With the state of the big boobs business today, virtually the only way that income levels like that can be achieved involve XXX, escorting and/or 'private shows'.
I also agree with you that it's just as easy for a feature to "party away" large amounts of money the same as a house dancer, but that's not the issue here. The issue is, as you say, a $70,000 or so annual income potential for a house dancer working 40 hours a week after paying $5,000 for her implants and gas money to and from the club based on a $79,000 gross, versus a feature winding up with the same $70,000 or so annual income after covering $60,000+ in total implant expenses + another $50,000 in air fare, hotels, cabs etc. to travel to different club bookings every week (which actually requires 6 or 7 days a week with travel time!).