Sales & Trading vs Prop structure

prop firms like FNYS is not like a prop firm that makes money off of commissions. They give you money in hopes that you make money and in turn their 50% share of the profit(I don't know if that is the right number btw) will put them in the green. I think you are thinking of those shitty scam prop firms

I should also mention your factors on what FNYS gives you are incorrect unless they changed in last six-twelve months.

edit

I am assuming flow is a declining business the last 5-10 years

This isn't a prop firm. This is a service.

No matter how anyone spins it, $8 per 1000 share traded is high vig. There are shops out there that cost .50 per 1000 shares traded... Why would you go to fny or whatever similar prop firm instead??? Do you want to make the owners more money off your intellectual cap??? All I can say is that the higher vig firms will pretend they are doing you a service... But not much is being done at all. They get you a bloomberg... But is it worth it???