Discount on loss

Hi,
Here some of the casinos apply 15% discount on loss,if you loose 5000$ they pay you back 750$ you can take it in cash or in chips to play.
BJ rules are 6d-SO17-DOA-DAS-65%pen-bonus on 6-78-777-5 card 21.
With basic strategy play the house advantage is 0.5%(If I am mistaken correct me please.)
Lets say, I have a bankroll of 3500$ for every seans and if I play 500$ on 7 box only one hand-dealer dealt for 7 boxes, I played the hand and If I lost, I take the discount on that amount and leave the casino-,Isnt it like this? (3500*15%) - (3500$*0.5%)= 508$ win on every hand.Am I right or not?
Waiting for responses. Thanks

There's no advantage,you only lose less.

The casino thought you lost.

Can`t we think it like this; a loosing box is -425$ and a winning box is +500$, we risk 425$ to win 500$.But I don`t mean to play all night long.Casino pay the discount when you finish your daily play.Because of this In a loosing freak -but not more than 3-4 hands play daily- because of the deviation they pay me extra 525$.
Its important that how often they pay this discount?
When 7box play If I loose all boxes, think that dealer makes a mistake and leave 500$ there,and this happens on every loosing hand. Isn`t it the same thing ?

" Can`t we think it like this; a loosing box is -425$ and a winning box is +500$, we risk 425$ to win 500$."

No,the casino is not giving odds. You're only getting 15% back of the money you will lose. Your negative expectation is .5% of $3500 minus 15% of what you lost. Think of it this way,you still lose,but less.

Thanks for your answer.After your last post I am trying at home what I`ve told you.It seems profitable till now.I`ve played 300 hands,which means 300 days.(I play one hand in a day, because they give discount daily.)I know its too less to test,I am going to test it till its going to be 10000 days.
So for every loosing hand I can add extra amount to my bankroll,think that dealer is doing mistake in every loosing hand,and leaving a box or more there.For 300 play I made bet 950,000$*0.5%=(4750)$.I received from discount 42,500 $.And add this amount to my bankroll.

It's not that straightforward to calculate your edge, but your plan will give you a healthy advantage in the long run, if the casino doesn't change the rules first.