[...] it's basically 1SP = 1RPP ( reward pool portion) [...]

That would only be the case if every account voted once in a certain time period with the same weight. But that obviously isn't the case.

The reward pool is finite, it is precisely calculated, you can get this number from the blockchain. I calculate it regularly in my calculations. It is given by the following formula:

reward_pool = reward_balance / recent_claims, where reward_balance and recent_claims are available values from the Steem API.

You can see it here at @penguinpablo 's SteemNow calc (explanation) and read about the reward pool (also by him) here. TLDR; it's about 48,029.695 a day (depending on a few factors).

The more that large stakeholders vote, the more they use because rewards are proportional to the total vote reward shares (rshares in the code) which are currently pending (i.e. before payout).

So this is what is meant by reward pool rape. Problematic term but widely used none the less.

If you knew this already I do not mean to be patronizing, just exact and clear.

This is all not to say that people dumping steem is bad for the price, which effects the market value for the rewards and thus reward pool, it's just a different thing.