Actually demand has being going down and rents have been trending down as a result. The main reason is less immigration and international students. I recall years ago every open house I would go to ended up selling above market value for cash from someone from overseas who "invests" their money on the back of locals trying to buy a house to live in for their family. The billionaires were not the ones to blame for this.
I don't doubt that immigration has probably marginally impacted the market, that doesn't change the fact that rent in NYC is still increasing YoY and is way too expensive.
And yes, the people extracting exorbitant rent cost are in fact the ones to blame. I don't understand people who seem to occupy a fairytale land in which they feel the need to defend billionaires as though they owe some fealty to them.