Holders do sell, and those who bought at the top will be the ones that will lose their money because those who bought Bitcoin at a much lower price and held their assets for a long time will be selling their holdings to take profit.

How to react to this market? It depends, but if you're a newbie, the safest approach is wait for the bear market to happen then that's the time where you can buy Bitcoin. It will take longer and it will test your patience, but if you're a newbie, that's better than buying at the top and getting FOMOed. If you know how to read charts then you're not a newbie already because for me, a newbie is a person who has little to no knowledge about something and in this case, it's crypto.

Holders when the market is pumping tend to sell a majority of their Bitcoins to take profit. Well at least that's what I'm doing. I'm gradually selling my Bitcoins as it goes up. Buying more when the market's going up is based on our decision already, and if we buy more Bitcoins, it's for the short term hold only and the risk is higher if we do it, but it's a calculated risk.

The best way in order for you newbies to not get FOMOed is to be patient. Be patient to wait for the bear market season to happen.