A.V.A Basic Coding C++

Morning Guys ! I was taking some lessons about C++ Coding.

I just started (4 hours of watching Crash Videos/Normal Videos(Pointers i checked)

So i want to ask you, whats the hardest about making a Hack for any Game/A.V.A

is it the thing:

*that you need the find the addresses (i tested it out on a cheap singleplayer Shooter with a 3level Ammo-Pointer which works)

or is it the thing:

*that it must be undected ? (i dont really know how the C++ file should be undected?

or what else? can someone just explain for short what i have to learn for

Another Question: Can i use my method on how i used my 3Level Pointer on the SP FPS' on A.V.A. too ?

I mean. i know that it isnt that easy to change any Value in a Onlinegame' with CE thats why im asking me how do i can change it anyway through CE ?
Im really getting used to concentrate in things i wanna learn. School for example..if i like this theme i do get an 'A on it ..if not ..hmmm ...back2topic:

Some more questions: Here are for sure other Coders who invested..some invested months some years..
Can you actually say me how long does it took to get into it ?