What about googling "freebitco.in review" or something like that? 99% of people don't know about that either?
When I google it, the top message I get is this one:

Note that it's not marked with

, so it's not a paid info, rather it's what most google users think of freebitco.in.
I dug a little bit onto Telegram and found a group of about 70 people, where I found the other user with the same problem, and nobody knew about the forum

Freebitco.in has over 45 million registered users. It's simply impossible to find a platform with that many users with no one complaining or hating it for this or that reason.
I'm sorry for your loss but it was no one's fault but yours.
I want some data that gives proof of that, as both explanations (hacked/inside job) for what happened are very, very unlikely.
I don't think your account was hacked, nor I think it was an "inside job". Most likely when going all-in you wanted to set the win chance to the maximum, but set to the lowest win chance instead. This kind of mistake happens sometimes to frequent dice players(happened to me too, but not on this site).