What is the source of income and the maintenance of the work of the exchange, if you claim that investors will receive a 100% return?
As an income, the exchange will receive a percentage of transactions. And also Stoxum token holders receive dividends on 100% of the platform revenue depending on how many tokens they have. You can see the calculation example in WP
https://stoxum.org/whitepaper/stoxum-en.pdf