i dont understand why i need a more expensive scope ? can you guys explain to me in a simple way thanks
You probably don't.
You may well be fine with one of these:
https://www.eevblog.com/forum/testgear/new-2ch-pocket-dsosg-sigpeak-dso2512g/, $70-80ish currently on Ali. Check that thread and see if it looks reasonable.
It may be a good idea to get one of these low end scopes (but not of the absolute trash category of course) which will likely serve you well in helping you do what you need to do and, importantly, provide a cheap way of learning what else you may need from an oscilloscope. When you learn that, you will already know when and why you need 4 channels, advanced triggering and other feature (or that you don't). If you do, you will have no difficulty with justifying spending more money on a more advanced scope, and that will be money well spent, as you will know better what you need and what to look for.
The problem with $200-300 scopes is that they are neither this, nor that. They are not much better than the sub-$100 ones, and they are way behind the $400+ ones. IMO they aren't a good investment: you spend considerable money, but you get much less than you would if you spent a little more, and by going sub-$100 you save a lot, but don't lose too much in features.
iam not a expert like you guys i dont design pcbs and i never wil ,i do basic stuff like installing rgb mods ,looking at schematics
Never say never :)
fixing crt tvs and monitors
These have their caveats related to working with HV, which I'm sure you are aware of, if you work on these devices. They apply regardless of the price and level of the scope though: you would need proper probes and know the techniques in any case.
old computers like commodore and pcs and some videogame console repairs
These should be fine with very basic scopes. More advanced scopes will be more comfortable to use, but the basic ones will get the job done.
not shure why i need a 4 channel scope that cost 500 euros or more
From a hobbyist's point of view... better scopes can sometimes help you become interested in things for which you need better scopes :)