Why are we so “reluctant” to take converts?

I put reluctant in quotes because I don’t know if it’s the right word. I see many other religions very eagerly taking in converts to their religion with a much easier conversion process. With Judaism, however, we do not let just anybody convert, and doing so requires a decent amount of study. I’ve seen religious groups with harder entry requirements (I have a friend who is a part of some occult group and their conversion ritual is hella difficult) still be more “open to conversion” than Judaism is.

Don’t get me twisted, I’m not saying that this is a bad thing. We have our requirements for becoming a Jew, and they happen to be higher than the requirements of becoming a Muslim or Christian (which are mostly just “say you are one”). Why is this? Why is our bar of entry high compared to the other major religions?