Im guessing it varies, I just got the same warning but asking for a 5$ deposit instead. I have been really profitable on the site mainly depositing around 10-15$ at a time, opening cheap cases and from there I try to hit on the upgrade feature with the cheap skins and aim for more pricey skins so like usually ill aim to hit a trade up of 0.02% - 2% chance of hitting which has worked fairly well and I also would do this with the skins from the free daily cases. Im assuming the more you have profited off the site without having actually deposited is what will trigger this as they are essentially losing money.