Basically this site,
Herearino (yes thats a refflink im sorry)
Allows you to deposit skins for points. You then use the points to bet on a roll and if you get a roll below what you were aiming for you win right.
Nicely it has a 50/50 option where you have a 50% chance to win with a 1.95 payout.
So like in roulette you can bet the minimum amount (20 in this case) and if you win great! bet the minimum again. And if you lose just double up. So 20 -> 40
If you win that one go back to betting 20 again. If you lose just double up again so 40 -> 80.
If the odds were a perfect 2.0 return you would always break even. but because its slightly below 2 you will lose a very small amount of coins although the doubling process will allow you to break almost even.
This just means a few wins at minimum bet will allow you to cover that and anything extra is profit. I went in with a FT guardian USP and came out with a AWP worm god FN, USP Torque FN, Galil rocketpop ST MW, Famas teardown FN and a FN Deagle conspiracy.
Looking back at the statistics it seems the site is actually fair in the rolls it gives as i am winning around ~50% (actually just checked i have won just over 50% at 1.01 ratio) There is also a page to "verify bets" Which allows you to see exactly how their RNG got the number it did. Idk if anyone wants to try and cheat it but meh, the info is there.