I honestly hope you are right, as I would personally be very glad if GBP/USD goes to 1.65.
But you are contradicting yourself. You say that:
With leverage 1:500 i open the same position for 300$, thus significantly lowering the risk of margin call. Stop out level is 10%. Meaning I have to have less than 30$ in my balance.
And I opened my position at 1.5350. Now it is 1.5288 - it fell from 1.5317 this morning, so now I'm 620$ back.
As per your numbers above, you got a margin call. If you hadn't come up with additional funds immediately, you would have been stopped out. FYI, the priced dipped to 1.5197 at some point 2 days ago. At that point, you lock a loss.
Increased leverage doesn't decrease the risk of margin call, it increases it.
You obviously know nothing about forex. Increased leverage decreases the risk of margin call. Why? Because you need less money to open a position with the same profit/loss per pip, which leaves you with more room and way higher margin level.
Margin level is the corelation between the margin required and the free margin (available cash). You divide the cash by the money needed to open a position. And the percentage represents your margin level.
For instance. I needed 300$ in order to open my position. I have 5grand - which leaves 4700$ free margin. So my margin level is 4700/300 * 100 = 1566.66%.
Margin level has to be 10% in order to stop out. Right now it's almost 2000%, since I am already at 1000$ profit, and I put a stop loss at a higher level of position value.
Of course if one is a greedy idiot an opens an insanely huge order that creates risk, but it is not due to leverage. It's because of stupidity.
I have 5 grand in my account so I could take up to 467 pips of loss before margin call.
I do not follow the chart 24/7 I just check it every morning.