King’s Indian Defense

Neopoliton it is!

#1
"Is it wise to use only one opening all the time?" ++ Yes, that way you accumulate experience

"can’t find the courage to try out another opening" ++ Why would you? To lose more?

You can use one opening all the time, no problem. The KID won't take you more than 15 years to master, if you study hard enough.

#6
"do you get from e4 to KID?"
++ You cannot. However Pirc Defence 1 e4 d6 2 d4 Nf6 3 Nc3 g6 is similar.

The Pirc / Modern is VERY different to the King's Indian.

Beat me to it!

To say the Pirc is like the King's Indian would be like saying a robbery is like a fire.  The first reaction from an 8-year old girl would be the same, she screams, just like Black's initial reaction is the same with the Pirc and KID, but the 2 are as different from each other as possible.  In one case, the fire, you run.  The faster you escape, the less carbon monoxide and other poisonous gasses you inhale.  With a robber with a gun, you hide.  You will never out-run a bullet.

The most similar opening against 1.e4 to the Kings Indian Defense is the French Defense.

After 1.d4 Nf6 2.c4 g6 3.Nc3 Bg7 4.e4 d6 5.Nf3 O-O 6.Be2 e5 7.O-O Nc6 8.d5 Ne7, the center is blocked, and the direction the pawns point dictates play.  White attacks Queenside, Black attacks Kingside.

In the French Defense, the Exchange is a lot like the Exchange King's Indian, and both the Advance and Winawer lines lead to the Blocked Center like the Classical King's Indian.

For example, 1.e4 e6 2.d4 d5 3.Nc3 Bb4 4.e5 c5 5.a3 Bxc3+ 6.bxc3 Ne7, Notice the blocked center once again, this time White's pawns pointing to the Kingside and Black's the Queenside.

It should therefore come as no surprise that White's best moves are 7.Qg4 or 7.h4.

Obviously no opening against 1.e4 plays exactly the same as the Kings Indian, but the French has the most similarities in terms of the general ideas behind the position.  The roles are of course reversed in terms of which color attacks which side of the board.

If we talk with white yes after 1) e4-e6 2) d3-d5 3) Nd2-Nf6 4) Ngf3-c5 5) g3-Nc6 6) Bg2-Be7 7) o-o...o-o and actually I think is just a variation Kings Indian Defense transposed (1.d4-Nf6 2.c4-g6 3.Nc3-Bg7 4. Nf3-o-o 5.e3-d6 6.Be2-Nbd7 7.0-0-e5)

Otherwise with black I don't find and the most similar should find in variations of Spanish Opening.

There is no white or black.  They are similar openings, period.  Regardless of which color you are playing.  The French Defense is the French Defense.  It is the same opening whether you control the White pieces or the Black pieces.  The game plays similarly as a whole.

Both openings frequently lead to blocked positions where play is on the wings, and both openings follow the same principles.  Attack the side in which your blocked pawns point.

So for the Kings Indian, that is the Queenside for White and Kingside for Black.

For the French, it is Kingside for White and Queenside for Black.

Two flaws in your logic:

1) We are talking about the Kings Indian Defense, not the Kings Indian Attack.

2) Of course the Benoni is similar to the KID, but the Benoni is NOT a defense to 1.e4.  The original question was whether you could play the KID against everything, and basically, that is a yes EXCEPT against 1.e4, and then the discussion was what KING PAWN OPENING is most similar to the KID, and the answer is the French, NOT THE PIRC!  There are 32 pieces on a chess board, NOT 16!.

The Benoni is NOT a defense to 1.e4.  So it does not qualify as a king pawn opening similar to the KID.

The strategies are not the same. Normaly when you play Kings Indienne Defense as black it is to play the attack strategy on the king with the two 0-0. As white normaly is to play an attack on the Queen's wing. 

If [for example] as white plays a closed Sicilian with "a Kings Indian Defense attack " 1) e4-c5 2) Nc3-Nc6 3) g3-d6 4) Bg2-e6 5) d3-Nf6 6) f4-Be7 7) Nf3-0-0 8) 0-0 "the Kings Indienne Defense loving player as black" will be happy to play this position because a similar strategy but if as white the closed Scicilian is 1) e4-c5 2) Nc3-Nc6 3) g3-d6 4) Bg2-g6 5) d3-Bg7 6) Be3-e6 7) Qd2-Nge7 8) Bh6-0-0 9) h4-Bxh6 10) Qxh6-f6 11) 0-0-0 it's not a "Kings Indian Defense attack" but a "attack 0-0-0 vs 0-0"  and  "the Kings Indienne Defense loving player as black" will [perhaps] be not happy because he has to play a different strategy.

The same goes for the French defense and the different variants that exist. These are not the same strategies as white or as black, therefore not the same way to treat the position as white or as black. 

You are looking at it all wrong.  Similarities is not based on which side you attack.  It is based on pawn structure.  You have a blocked center and the idea is the same, you attack on the flank where your pawns point.  That may be queenside in one opening and kingside in another, but the idea is still the same.  Attack on the flank where your central pawns point!  Just like how the petroff, Exchange French, and Philidor with 3...e5 4.dxe5 dxe5 5.Qxd8+ all have the same idea.

#17
"Similarities is not based on which side you attack. It is based on pawn structure."
++ That is why Pirc Defence is most similar to King's Indian Defence
King's Indian Defence: a7-b7-c7(c6,c5)-d6-e5-f7(f5-f4)-g6-h7
Pirc: a7-b6-c7(c6,c5)-d6-e5-f7(f5)-g6-h7

If you put out the "insignificant" fact that in the Pirc / Modern it is White the one who is attacking the kingside, and Black is advised to delay kingside castling, or forget about it alltogether, then yes... you are right, the two openings are very similar- lewaving aside that they have few things in common.

And also, that in the Pirc / Modern white rarely has to close the center, as his pawn at c2 and not c4 means that the d4 square is not weak.

#19
"in the Pirc / Modern it is White the one who is attacking the kingside"
++ King's Indian Defence and Pirc Defence are similar from the black perspective: the plan is to exert pressure on the dark squares with g6, Bg7, d6, e5. Then it depends on what white does.
Here is a Pirc game where white attacks on the queen's side
https://www.chessgames.com/perl/chessgame?gid=1068052 
'White attacks the queen's side, black attacks the king's side' is true in the Mar del Plata Variation of the King's Indian Defence, but not always.
In the Sämisch Variation white attacks on the King's side with f3, Nge2, Be3, Qd2, O-O-O, h4, g4.
https://www.chessgames.com/perl/chessgame?gid=1067300
Bronstein as black won several King's Indian Defence games with attacks on the white queen's side with a7-a5-a4-a3.
https://www.chessgames.com/perl/chessgame?gid=1033779 

yes u can, by 2. c4 then a delayed d4 or 3. f3 to transfer into samich

play a diagonal based strategy. @OP