I had several websites where changing the URL schemas resulted in Google rank dropping, resulting in advertising revenue loss. I don't see I can be more honest than that. And frankly, you are not just unfair, you are being rude.

You changed them without redirecting properly.

Actually, tell me a few of these websites.

Those are porn websites, so I'm not going to share them. And there are only 2 kinds of redirection, permanent or temporary so it's pretty hard to do it incorrectly.