Caching can make sense in more situations than "too many users running the same query at once". For basically anything slow that you'd like to make faster, you

Caching can make sense in more situations than "too many users running the same query at once". For basically anything slow that you'd like to make faster, you can weigh the downsides of caching against the downsides of optimizing its performance in other ways. In a startup context, often some (judicious) caching is preferable to spending a bunch of time carefully optimizing some code that's going to change or be thrown out in a month anyway.