Welcome to the forum,
To start with, I like how they have security, the fact of placing the words or phrase to save the ceunta seems excellent to me, also the fact of requiring 2FA, I also did some tests and verified that according to the pools of insanity, The 500xBit.com platform does comply and does not manipulate the market movements in its favor, which speaks highly of the honesty of the site, and this is something that is far from scams. It would be excellent if you considered that they could take other options of alts, at least the most fashionable ones, DOT, UNI, BNB, ADA.
Is it legit will you get the bitcoin though if you win?
You can try it yourself, they have automatic payment system and they don't charge you for the transaction fee as well as withdrawal fee. You can deposit any amount to test the website. I tried already your website through the demo bet it was really entertaining and I won good amount but it's just a demo coin I will transfer coins when you officially open your website since I see that it was just a soft launch but I think it's good already.