Hate to be boring or negative even but if the plan is just to sell and everyone has a similar plan can you spot the flaw in the plan to this ever happening
if demand is strong enough, it doesn't matter.
and when the bubble is happening, greed takes over. most people either sell way too low before price goes parabolic, or they wait until after price crashes out of greed. very few people get to sell the top.
Talking about greed, people will probably wait for ath and sell everything then the bubble will burst out. Hence, selling on top will br their goal. Demand will determine the price hence the supply and bitcoin halving will not be a factor for now.
Just note that we should know when to reap our profit.