Certainly one reason that kepts bitcoin remain stable these days its due to many demands came in and market recovery is having continues improvement after long bearish months.
if bitcoin recieves too much demand then the value shouldnt become stable but it will become unstable . Unstable in a form of continous growth . Demand and the willingness of people to hodl is also the reason on why bitcoin is not going down .
It will come down or won't come down will be because of Tether.
bitcoin can go down at some point because the downfall of the price is normal and will be needed before we see another highs but i dont think that tether is the one that responsible for this. As i stated earlier , the ups and downs are only caused by the demand and other factors .