This is the story how my Steam account got hacked:
I was talking to a friend of mine at a party and I just bought a new game (forgot which one). He told me that he thought about buying the game as well and asked if I could let him try it out one time. I said "sure, just message me and you can log into my account and test it". 2 days later, he wrote me on steam asking for my login data and I thought nothing of it since we spoke about it in person, so I gave him the info. Turned out, his account got hacked and the intruder basically got a two for one special by just asking lol
Steam support rectified the situation and didn't even scold me for sharing my account which is clearly a violation of their ToS.