isn't that basic math 😅 so what do you have to worry about

hello, can someone explain the following to me, I have 1000 dollars in cryptos, the market drops 10% and I'm left with 900, then it goes up 15% and I'm left with 936 for example, all the coins are higher than in the fall and yet I have less and less capital, I can't find the explanation for this,,, even though the cryptos are recovering my capital decreases every day, I feel scammed