These are high leverage Fx traders, so they use 50x-400X ( they can make 50%+ a week easily if they catch the right trade). The "scam" is that some traders might have 50 accounts, 49 blow out, and they only show you the one that did not (because the trades there worked for some reason, slightly different timing and/or algorithm and/or pair), and they will have all the documents and the audits you want. The likely outcome is that you follow that account and it blows up after a couple of months. Some are just doing pure martin gale. I actually followed a trader once︀ and made 100k+ with 10k, but I was willing to lose that 10k at any︁ point. If you ask these traders, that you will only pay the fees after 6︂ months or one year, they will stop responding haha
That's why they either hide the︃ balance (it is usually small as they spread it over many accounts) or it wont︄ exceed 5k, I've always wondered why they don't invest more in such "profitable" strategies until︅ I understood the full picture and that they have 200 "strategies" blowing up in the︆ background.