word-request
You know, the friend that everyone in the room will shut his mouth before he finishes his sentence knowing that it will very likely to become true.
Tom: I don't think this nice weather will last very long.
Everyone: Shut up, it will rain now if you say that.
In general, you can say things are worn out.
What do you expect? I've been using them for the past two years. They're worn out!
For many objects, there are alternative words, but they're less general:
For your car example, I'd say dilapidated. This word works best for larger, more complex objects. A house or car can be dilapidated, but the phrases ?dilapidated keys and ?dilapidated headphones sound weird to me. You can also say a car is broken down, but only if it doesn't actually move.
For keys, I agree that rusty works, but only if they're actually rusty. If they're worn down, I'd say they're worn.
Sometimes you don't need a special word. I might complain about my broken old headphones. You could also say they're in a state of disrepair, but it doesn't sound very conversational to me.
? This symbol means "This phrase is of dubious acceptability. I suggest you avoid this phrase."
There are a few words for this... I think the one that best fits your description is "yes-man":
a person (especially a man) who agrees with everything that someone says : a person who supports the opinions or ideas of someone else in order to earn that person's approval
The first one to come to mind was "toady", which has the added benefit of being a noun and a verb:
Noun: a person who flatters and ingratiates himself or herself in a servile way; sycophant
Verb: to fawn on and flatter (someone)
Sycophant is also a good word:
a person who seeks favor by flattering people of wealth or influence; parasite; toady
There are a bunch of other options, though, including "flunky":
Best Answer
If the person is specifically predicting doom and disaster (as opposed to just general predictions), they are A Cassandra (From mythology):
https://grammarist.com/usage/cassandra/
The original mythology held that as well as being given the gift of foresight, Cassandra was also cursed so that no-one would believe her. Although today's usage is more generalised in that the speaker can merely be unpopular for their predictions, whether or not they are believed.