The issue with Copytrading is that most platforms don't really give a backtrack of the performances of expert traders that users are supposed to copy. This can result in following the "wrong experts" thus leading to more losses. So, how can one find the right copy trading platform in the first place?
You're absolutely right, blindly copying a trade of someone not known can lead to losses or dancing to the tune of someone with an ulterior motive, that's why it's good to DYOR before following anyone, and I've seen a few platforms doing it better, like Bitget, OKX eToro. And I know Bitget often display the traders success rates over time, which can enable you to pick right. You can also use a trader's strategy as an insight to build yours.