would BFL start mining for "future returns"?....which is very uncertain and risky as bitcoins rates fluctuate all the time...
going as high as $30 at a time to the lows of $5.....

rather then selling each machine for probably 2-3 months worth of mining each....in advance! (and when everyone has them perhaps longer than that)

Infact the more machines they make and run....the less and less they make per machine....to the point where an upgrade would be necessary..or to lower the number of machines.....and if the question is about integrity (i.e. them using advance payments to run it themselves before passing it on...well that would kill their business instantly...as the difficulty levels will increase very quickly and no one will buy their shit.

this analogy applies to websites on flippa.....people sell their genuine adsense earning websites...for 5 times ...10 times the monthly income.

why don't they keep it?.....because of "uncertainty" of the future...

can ANYONE guarantee the Exact number of bitcoins u will make after getting these asic machines? NO....hence the risk!

butterfly labs wants to pass this risk on to us....and it is happier with perhaps a lower but safer investment...its machines!

its all about risk to reward ratio...everyone is at a different level....and what may be "hey why isn't everyone doing this.."
would be  "why the hell would anyone do that" for others.

and if the "gold tool sellers" had enough man power...their "costs" would also increase... unlimited manpower would work against them....because "finding gold" is not guaranteed....it would simply increase their chances of finding it..or lets put it this way, it would increase the SPEED of finding the gold, just like bitcoin miners.

on the other hand...if they had unlimited "customers" for their gold tools...their profit is locked in....while all the gold miners are competing against each other...(like bitcoin miners are).....a simple matter of supply and demand....

but bitcoin miners are additionally making the system more stable and faster....unlike those gold miners....