The reason coattailing someone else's trades doesn't work is because you cannot read their mind. They usually don't tell you where they've placed their stoploss or where they intend to take profits, nor their timeframe for the trade, plus by the time they have posted the trade, they are already in, and if they got the direction right, your entry will not be as good.
I never enter stops unless I will be away from my desk because, like you, I have seen too many times when the MM swoops down, collects my shares, and moves the price right back up. I do, however, always know the price point at which I consider the trade has 'gone wrong', and set an alert on my platform at that point, then reevaluate and sell the shares if necessary. Works for me.
Newly