By definition ‘stable’ coins have to offer always fixed or 1:1 exchange rate to the fiat or to a major crypto-coin.
A trader can not make money on trading stable coins - it does not appreciate against fiat and may actually lose a fraction or a lot of the value.
If a trader buys for ex. USD based stable coin and sells it immediately they will lose somewhere from 0.5% to maybe 2.5% or more of the initial fiat amount.
