Ok, so you send 20,000 free signups a day. that's $40k-80k in revenue daily on a pay per lead model...
Go try your method on a pay per SALE setup. Now how much money are you making? I'm gonna take a stab in the dark and guess nowhere close. Your lead quality is probably absolute shit...
Now if you were running a dating network, would you want to pay out $40k+ daily for a shit pile of worthless leads? Probably not...
If your lead quality was even half decent, they would pay you and beg for more signups. It's not them dicking you here, it's you looking to dick them. No one with any business sense is going to sit back and let you pound them in the ass til they go broke...
Seriously, try promoting on pay per sale and see how well your traffic performs...