Whenever I encounter a "data lake" it's just a bunch of random CSV and JSON files on S3, and a bunch of half baked Python scripts to query it. And usually somebody tells me it's "big data", and that's why it is has to be that way. So I check the size and it would easily fit on a laptop from 15 years ago.
Bingo. Double points if the infra surrounding this costs more than a maxed out MBP a month in spend
The first time (and all others) I heard "data lake" my brain instantly translated it to "somone elses problem". As in the very name implies a carelessness to just dump whatever and somone else will take care of it.