Bottom bracket lifespan
 

I have a bike with about 3000km on it and in the last few months there is a noticeable creaking off the drive train, really only heard when going up hills excess of 6%.
There is a brand new chain on it, and the chain ring bolts have been tightened numerous times.
The bottom bracket is a BB383Evo, and the crankset has carbon cranks.
When turning the cranks they feel rough and it can also be felt vibrating through the frame.

Is it common for a bottom bracket (assuming thats the problem) to go so early?

386 evo, maybe?

The bearings? Sure. Is it press fit or theaded?

Would be unusual but not unheard of. Take the chain off and spin the cranks. See if they feel rough or noisy. If so, you are almost certainly have the problem diagnosed.

He already said that it was rough and noisy and he felt vibrations

Happened to the girl's bike in less mileage than that. Some heavy-rain rides were all it took.

Brand new chain and creaking? Sounds like your chainrings need to be replaced.

He didn't say he took the chain off. Doing so eliminates other components from the equation. If chain is on, could be chain/chainrings/cassette/freehub/RD pulleys etc.

You want to isolate the alleged bad actor. It probably is the BB but you never know.