>>1813023If the chain wears out badly it starts slipping, which can be dangerous but is mostly just extremely annoying. Plus as the chain wears out it wears the gears faster, making it more likely that when you do change the chain it won't fix the problem (or even make it worse).
Bad cables make braking and shifting worse, but for the most part if you're not after optimum performance then if it ain't broke don't fix it.
Don't really know what happens when rotors are worn out since I'm a rim brake chad, but if your brakes still work fine and they aren't bent or anything I'd say don't worry about it.
>>1813024Also if the west hadn't decided to nuke their own economy in exchange for minorly inconveniencing a country they dislike over a region that doesn't want to be ukrainian in the first place.