So, don't sell to them instead, hold patiently and in matter of time depending on your goals and assets values, you could imitate them (whalers) or could even be one in the future.
Whether you sell your coins or not, the whales knows when to take advantage of the market so it's not as if when you sell to them that you are at
loseloss while they win. If a whale wants to manipulate the market, he can buy huge amount of bitcoins and after the price skyrockets he can decide to sell immediately and take profits but since they already know the potentials of bitcoin, most of them no longer sell their bitcoins after buying but instead they HODL for long term profits which will be huge and massive. How can you imitate a whale when you are just a minnow, lol. Whales a big investors with high sources of income and wealth so you can't imitate who is bigger than you in terms of investment.