Why can't I pickle dataclass with defined __dict__ property?

Question

I have simple dataclass which has __dict__ defined, using asdict, but pickle refuses to serialize it

import pickle
from dataclasses import dataclass, asdict

@dataclass
class Point:
    x: int
    y: int

    @property
    def __dict__(self):
        return asdict(self)

p = Point(10, 20)
assert p.__dict__ == {'x': 10, 'y': 20}
print(p.__dict__)

b = pickle.dumps(p)
p2 = pickle.loads(b)

print(p2)

outputs

{'x': 10, 'y': 20}
Traceback (most recent call last):
  File "C:\Projects\others\pythonPlayground\data_class.py", line 18, in <module>
    p2 = pickle.loads(b)
  File "C:\Projects\others\pythonPlayground\data_class.py", line 11, in __dict__
    return asdict(self)
  File "C:\ProgramData\Anaconda3\envs\pythonPlayground\lib\dataclasses.py", line 1075, in asdict
    return _asdict_inner(obj, dict_factory)
  File "C:\ProgramData\Anaconda3\envs\pythonPlayground\lib\dataclasses.py", line 1082, in _asdict_inner
    value = _asdict_inner(getattr(obj, f.name), dict_factory)
AttributeError: 'Point' object has no attribute 'x'

why is that and how to bypass this problem? Or is there any other generic serialization library which can take almost anything, and serialize it to bytes, and it would work?

In the end I tried 2 different packages: dill and cloudpickle and dill works, while cloudpickle not.