Vedran is completely wrong what you say.
The logic is exactly you go short using the sell price and you sell your position with buy price (buy price > sell price so in a short position is worst situation).
I make you an example my friend so you can get what I say:
In the image above you have for Wirecard:
If you go short in that moment you will borrow those shares at 2.861
If you would want to close your position exactly on the same moment you opened it then you will close the position at 2.900.
Let’s say you bought 400 shares. So we will have:
(2.861-2.900) x 400 = -15.6 €
So you sentence:
“Using logic that you short using sell price and the profit based on buy price, you would be in profit always and could just short and profit on spread. Because Buy price is always higher then sell price.”
means you have no idea what is short.