Or are these declines an intervention by whales for market picking?
Investors are taking precautions as there is signs of a bearish Market. People are converting their profits and coins to stablecoin to avoid losses and this is causing a sell pressure and when there is not enough buyer the market dump and causes huge fluctuations in price. Whales are also selling because they affect the market the most just as the market is been affected.
You can decide to sell and wait for lesser price to buy back in or just keep holding your coins, never the this only temporary as the market will recover and majority of the losses can be gained back.