For stock, a percentage is typically given, because it doesn't matter what dollar amount one arbitrary unit gained. What matters much more is "if I had invested

For stock, a percentage is typically given, because it doesn't matter what dollar amount one arbitrary unit gained. What matters much more is "if I had invested $1000, how much is it now". Saying that it gained $30 is meaningless without knowing the previous value - if Bitcoin gains or loses $30, nobody cares, if Ethereum gains $30, that's over 50% gain in value.