You can generally assume at any hotel with keycards, that any other guest who wants to can get into your room.

The only question is whether they do some hacker shit, or whether they just go to reception and say "My keycard isn't working, I'm in room 123" and reception gives them a new keycard for room 123, with no ID check and no questions asked.

Luckily thieves are relatively rare and 97% of hotel rooms just contain a suitcase of second-hand clothes.