Oh, they still work, but the data gets corrupted. I have at least 4 flash drives here in front of me, from 8 to 32 gigs, that tend to be problem children. Short term, great. Long term, not so much.
Wow, you do have some bad luck. I have multiple brand flash drives (over 20) from the last decade and I have only had one give me some intermittent issues.
Knock on wood.....