Why not just ask a banker?
Being card counting is such a good deal financially, why not just go to the bank, tell the loan officer you need a $10K stake to begin a serious card counting career, and get a loan that way? Bankers are smart guys and can understand the mathematics of counting.
I wonder how long he'll laugh. Now I am not 21, have good credit, own a home, and if I were to suggest I was going to take the money anywhere near a casino, they'd laugh at me too. Unless of course I was willing to put my house up as collateral. Why is that? Because bankers are smart guys and they understand the mathematics of counting.
Let's look at the things that could go wrong with such a deal. The simplest one is I could just have a string of bad luck and lose all the money at the table. It can and has happened. It can happen in one night. Then there's other matters. With all the stress, I could develop an addiction and lose my money that way. Or maybe I have a great winning night, and bring a whore up to my room to celebrate, and when I wake up she's gone and so is all my money. Or someone could see me cash out, follow me outside and rob me in the parking lot. Or someone could pick my pocket in the men's room. Then there are a dozen more things I can't think of right now. True, most counters are disciplined enough not to let these kinds of things happen, but we are also disciplined enough not to go into debt for a bankroll!
My advice is to get your experience in at the $5 table. You're only 21, that's barely old enough to even play in most casinos. Bring a $500 stake and go home empty pocketed a couple of times, then ask yourself if you want to repeat the experience with money you have to pay back to someone. Or maybe not. If you bring $500 to the casino, your chances of going home with $1000 are greater than your chances of coming home broke. And if you do lose it your chances of getting another $500 stake are much greater than getting a $10K one, especially if you have gone into debt. See what I'm getting at? For a guy like you, screw the bankroll criteria, worry only about the technical aspects of your game, and get out there and roll the bones with what you've got.