Hello, can anyone help explain this to my sister? I am so tired of repeating it.

She invested $2,000 in cryptocurrency.

Then the market fell by 10%, and her portfolio decreased to $1,000. Then the market rose by 15% — but instead of going back above $2,000, she only gets $1,750.

Although the coins are worth more than at the moment of the fall, her total amount is still less than before. She doesn't understand why this is happening and feels like she is being deceived, but that's not the case.

Can someone explain why this happens in a simple way so she can understand?