You seem to have forgotten Madrid's track record so far. They are a big club that has won La Liga and even the Champions League several times. Their mentality has been formed quite well, even though after being left behind by several players like Benzema, it is very likely that they will still be able to show their best performance. So even though it's too early to say that fan optimism is well-founded. Because as fans we will see for ourselves whether Madrid is able to maintain its existence again in La Liga or not.
It cannot be denied that markets can be manipulated by those who have strong enough financial power, but this is not a common occurrence because most markets have rules, regulations and supervisory institutions that work to prevent and overcome manipulative activities in order to maintain market efficiency by respective state authorities for the stock market.
Acts of manipulation are illegal acts that harm many people, of course this will always be anticipated even though there are still some bad actors who succeed in doing it.
So the point is don't influence and look bad at these things because in my opinion being manipulated is not a common thing to happen.
Vinicius Jr absence certainly had a big impact on Madrid attack line, because around 30% of Madrid attacks in several matches were based on Vinicius Jr agile movements. Ancelotti will definitely change his squad formation where Vinicius Jr absence needs to be covered, for example by including Diaz or Joselu. But that won't be enough to match Vinicius Jr.'s moves.
Of course, because Vinicius is their mainstay player at the moment, Vinicius will be out for 6 weeks and in my opinion there will be many other Real Madrid players who can compensate to maintain team stability / performance.
Maybe if you go up against a team with good quality, it will make Real Madrid a little difficult because of the absence of Vinicius, but for other matches in La Liga I'm sure there will be many other potential Real Madrid players who can cover.