[EdgeExplorer]

There are better answers in the linked book. :)

But no, nothing is sacred. Not only that, from a historical perspective, the current pace of language change is shockingly slow because of the impact of media. It would not be at all unusual for a word like drop to move entirely to a new metaphorical meaning causing other words to have to fill in the gap. In German, you "let fall" something. Even if anything was sacred, "drop" would be far, far from sacred. It is very easy to replace.

(The closest thing to sacred is words for familiar, every day objects and people. "Mama" is pretty nearly universal, for example. But even so, we literally don't even know where the word "dog" came from, so no, nothing is sacred.)

There are many many examples if you search (or even better, read the book!), but here are a few:

"silly" originally meant something more like "blessed"

"fear" meant "danger", referring to a thing feared, not the feeling

"nice" meant "foolish" and literally comes from roots mean "not knowing"

This kind of change in meaning is very, very normal. This is just how language works. I really think you will enjoy the book. The author is very easy to read and covers a ton of linguistic ground.