I am not seeing any stability of bitcoin rather a bearish market of it. This I think is normal, last year this was also felt. Plus, we had been hearing news about the government's action against bitcoin so this factor would be affecting.
Yes, bitcoin is not stable at the movement instead it is under pressure to go down some more if this bearish market continues for a longer period. The main reason for this bearish market is all governments want to regulate this market and they want to track the money flowing into crypto markets but as of now they do not know how to do it so they are targetting crypto exchanges.
Is there more manipulation by big whales, speculators or big institutional investors trying to profit the flavour of the moment?
I feel that there are big players "pumping and dumping" in order to manipulate the market to stabilize price and "control" in a certain way the price fluctuation.
I don't think prices are down due to any manipulation by big whales.
Is people hoding less their coins?
I don't know about others but I'm now holding more coins than last year because I bought more in this down market.