This is why. It is tactical mainly, but the main strategic idea that helps with the compensation is that black's king is out in the open, and black's pieces are not developed. White has two pieces developed, and will be able to easily develop. Black also has to be careful to not get checkmated, and it is a position that is not easy to play either.
Hope this helps.
It seems to me that if I'd done this and they'd responded with fxe5 then I'd most likely be down a knight without adequate compensation. I could go qh5+ but after the g7 pawn moved to g6 if I went qxe5 then the second pawn still wouldn't make up for losing the night and my opponent could play qe7 which would leave me with a queen swap at most?
I'm a beginner player so what am I missing here?