ideally they wouldn't need to launch a DEX. however, they know the market is heading that direction---see ethfinex for example--- so they're adapting. they know damn well it'll dig into their exorbitant profits, but what's more important for them is market consolidation: they need to secure market share.


i don't think the details are publicly available yet. but here's my personal thoughts:

binance will use a BNB-powered blockchain. regarding fees and potential profit, it partly depends on how the underlying blockchain is secured. is it mined? hybrid POS? a private chain maintained by binance? in most scenarios, binance is likely to be collecting much or all of the gas fees paid to trade on the DEX.

so first, they're collecting BNB gas fees (and perhaps withholding it from market, increasing the price of BNB).

second, they inflate the price of BNB by increasing demand for it: now there's an entirely new use case---it's not just an investment because of their buyback/coin-burning program or for discounted fees anymore. now you need BNB to trade on a DEX (and i'll bet one of the best DEX on the market).

third, they inflate the price of BNB by reducing supply: if everyone needs BNB to trade on the DEX, they first need to buy it at spot then hold it in their wallet for future transactions.

i think they're trying to build an economy around BNB. since binance is the only place BNB can be used, it reinforces the incentives to use their exchanges. and also, last i heard, the binance team holds 80 million BNB---if BNB rises in value, they profit greatly.


they're offering people a choice:

use our centralized high-speed exchange like before OR use our DEX which economically reinforces our business and retains our market share