I should have known...

I put the purple trend line at least half an hour before it dipped, i should have sold it after seeing the trend kept going downwards.
And of course Robinhood had to do their daily maintenance where basically you can't trade BTC during that time. I was stuck & helpless watching BTC dipped right before my eyes...
Lesson learned: Don't use Robinhood for Bitcoin trading, and always trust your gut and don't get greedy.