Why can't I run a file delete daemon (doesn't delete anything) in a docker container (from python:3.7-slim image)?

Question

Python

Tried like this:
Dockerfile

FROM python:3.7-slim
COPY .  .
RUN python -m pip install -r requirements.txt
CMD python daemin.py start && python main.py

The container says it's running, but nothing happens.
daemon.py

import os
import time
import sys
import atexit
import signal
from pathlib import Path


class Daemon:
    """A generic daemon class.
        Usage: subclass the daemon class and override the run() method.
    """
 ....

class MyDaemon(Daemon):
    def __init__(self, audio_directory, pidfile, every_n_minutes: int = 8):
        super().__init__(pidfile)
        self.audio_directory = audio_directory
        self.secs = every_n_minutes * 60

    def run(self):
        while True:
            wav_clean_deamon(self.audio_directory)
            time.sleep(self.secs)


if __name__ == "__main__":

    daemon = MyDaemon(
        audio_directory=str(Path(".").resolve() / "temp"),
        pidfile="/tmp/mydaemon.pid",
        every_n_minutes=1)
    if len(sys.argv) == 2:
        if "start" == sys.argv[1]:
            daemon.start()
        elif "stop" == sys.argv[1]:
            daemon.stop()
        elif "restart" == sys.argv[1]:
            daemon.restart()
        else:
            print("Unknown command")
            sys.exit(2)
        sys.exit(0)
    else:
        print("usage: %s start|stop|restart" % sys.argv[0])
        sys.exit(2)

grpc service starts in main.py

if __name__ == "__main__":
   server = grpc.server(futures.ThreadPoolExecutor(max_workers=10))
   address = f"localhost:8181"
   server.add_insecure_port(address)
   server.start()
   server.wait_for_termination()