Everything in crypto is possible. Either they will sell them all at once or they will prefer hodling, there are always inevitable events in the market that create a huge negative impact and leave the market dumping. However, we should not panic in all these events as these things are not new here. Bitcoin has always a strong foundation, so whatever attacks that it may encounter, it will surely find its own way to survive and continue to stand firm. That is why there is no room for worrying, as it may lead to depression when things seem to be uncontrolled anymore.
We don't have to worry about bear market events because any upside impact will decrease eventually because the market is forming a defensive position for a certain price before the recovery process higher and of course the next bull market, so no need to worry if you hold bitcoin or top altcoins in your portfolio.