Hello
When Dash increases and the BTC decreases, it means you have bought a certain amount of Dash and accumulated Dash. So when Dash increases you will sell DASH to BTC and your BTC number has increased compared to the original time. So you are profitable.
Conversely, if you keep DASH and DASH prices down compared to BTC, you will lose BTC and you lose money
So if you now have DASH in your wallet, please wait for DASH to increase compared to BTC, then sell it to lock in your profits