Good question. Hope this will help you out.

What the casinos call the "hold" is actually the casino's net win. Say that a game is rated at 98.5% payback (expected return). That means that the hold is 1.5%.

Most VP players don't get the expected return because of bad playing strategy. If evrybody played a perfect strategy, the casinos "hold" would be less.

This does not affect the RNG. If it did, then it wouldn't be a true RNG, and somebody on the internet would have outed it.

Does that tell you what you want?