yeah i think the first thing to consider if you want to try out 1.e4 e5 play is what to do against the kings gambit. luckily all lines against the kings gamit is equal so just pick the one you like the best be it a crazy or simple one. i prefer to play 2.exf4 followed by g5. i got beat up alot in the start but now that i start to learn it it seems kings gambit players find me annoying to play against
so why did YOU leave 1.e4 e5?

I used to play e5. When I discovered "Chess Openings: Traps and Zaps" is trash, I abandoned e5. I started playing c5 then.
I stopped playing e5 when I was a kid.
The kids who were better than me played the ruy lopez or kings gambit. (They also didn't play 1...e5 and I wanted to be good like them)
The kids who were worse than me played something passive like the 4-knights with 4.Be2 or d3.
I didn't put much consideration into it (I was about 11 years old). I just wanted to win ASAP with tricks, and I didn't know any against the things my opponents played.

I'm still only a class D player, but I haven't left. I did for some experiments with the Sicilian and Pirc, but today I play the Petrov and I like it a lot.
By the way, the O.P.'s line of 1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. Nc3 is not a great opening for white because of black's move 4...Nxe4 5. Nxe4 d5

e4 is mostly boring and studied all the time and e5 makes me feel that i'm not good at chess as everyone is playing the sicilian and i have to be stuck with some boring two knight s defense or italian game.

well the italian can be quite boring, but so can the c3sicilian, exchange french, exchange caro kann and so on:) about the two knights, i think you would get a nice suprise if you look closer at it. here is the mainline or at least the one i face the most after Na5.
I am scared of facing King's Gambit even though I play it myself as White.
My eyes light up when I get 1. e4 Nc6 2. Nf3 - its the Open game again!