The only thing I don't understand is how your platform benefits from allowing to trade from $100 and such little shares
Actually, that's exactly a new window of opportunity. Micro investors, who are interested to invest just a bit or invest with a spare cash, or simply gamble with a little of money represent an already huge and growing market. Take a look at Acorns, or Stash as examples in classic finance.
So basically the strategy is to attract more small investors and make profits on the economy of scale?