Simply because of it's good development as it's market value going up, also it's gas transaction fees are going to get high just like bitcoin platform. Ethereum network are widely use in cryptocurrency industry thus it could handle such great and large network for a crypto business. And by this,many turn into bsc smart chain network aince the gas fee is lower than ethereum network, however if bnb price gets up, it would end up like ethereum network that the gas fee transaction goes also very high.