You didnt curious why would he said you could gain 300 from 100 in three days? From that point, its kinda hinting the guy was a scammer cause that is a short time to earn that provided that he will not do it on a known process such as trading. Also why would you trust someone to give your bitcoin its wrong move. I hope you already learn the hard lesson. Reflect and focus more on knowledge cause it can be your skills to earn in a right way. Avoid talking to strangers cause majority of someone just pm you is after your money.
The scammer probably established trust and we know how most people are when someone they trust is promising them something, pretty sure that they're going to be ignoring the flags because they want to see the good in people. Maybe OP hasn't heard of the saying that if something is too good to be true, it probably isn't.