On the contrary, owning 5% of the bankroll usually means you get 5% after the house cut. I'd estimate it to be about 20%, meaning that you'd only get 5% of 80%
Well thats does depend on the casino i know of a few that give most the edge to the investors.
Bitvest being one of them its 1.7% edge investors get 1.15 and site gets 0.55% the rest is based on how much is lost and your share of the investment.
Then again you have to read sites carefully because some take the full edge on investment based gambling sites as a fee.
I'm pretty sure this could be a universal game plan tho i tried it with dice, plus there is other methods that can be stacked with this to get even more back out of it.
So the best thing that you have to do is just to play with small amounts so it wont be that worst if you are losing some money with gambling.
If you gamble on a low-traffic gambling site that gives a large portion of the edge to the investors, you could easily become a big fish. You would win less, but also lose less. So it's basically softening your wins and losses. The question is - For better or for worse?