If Chess is a draw game then why does white lose here?

2 dubious moves

#31
"what is the value of strategy and positional play?"
The essence of chess is to avoid mistakes and to prey on mistakes by the opponent.
Strategy is long term means of exploiting mistakes.
Sound positional play is a means to avoid mistakes.

@tpr is correct in theory. However, his ideas don't work in a practical game yet. Many great chess players and authors have from Steinitz to Silman have stressed on the importance of accumulating small advantages. (Un)fortunately the computer's analysis is still not deep enough to tell us if a position with many pieces on the board is a win for one side or a draw, so the art of accumulating small advantages still means something, and this is how games are won at the top level usually (if one player does not make a gross error).

#34
Accumulating advantages is an illusion and no one has ever won a game by it at any level.
You win a game by exploiting a mistake by your opponent.

#35 Yes, yes basically you are right and the Silman school of chess and the thousands of people who believe in it are wrong

@tpr Accumulating advantages = exploiting a mistake by your opponent.

Accumulating advantages is harder imo,
The game is too tactical.

#36 Yes indeed, Silman is wrong on more than that.

#39 Yes indeed, most mistakes are of tactical nature and require tactical awareness to exploit them. Some mistakes are of positional nature and require more strategy and endgame tecnique to exploit.

#38 You cannot accumulate advantages. Either your opponent makes a mistake and there is an advantage for you to exploit to a win, or he did not make any mistake and so you have no real advantage.