As a market approaches being perfectly competitive, risk-adjusted profits approach zero. If I understand correctly, that's basic economics, and it's not limited to just Bitcoin. If you want to make money in a market, you either need a sustainable competitive advantage or non-average risk tolerance.
What could amount to a sustainable competitive advantage in Ⓑ? Reputation isn't it: the whole point of Ⓑ is that Ⓑ100 is computationally infeasible to counterfeit and equivalent to any other Ⓑ100. If you developed an especially money-efficient SHA-256 chip, or for that matter a pure Ⓑ-mining chip, you could perhaps remain profitable mining with it for a while, until the market caught up with you. (Does that depend on whether you use the chip yourself or sell it into the mining market where people compete with each other?)
What could amount to a sustainable competitive advantage in Ⓑ? Reputation isn't it: the whole point of Ⓑ is that Ⓑ100 is computationally infeasible to counterfeit and equivalent to any other Ⓑ100. If you developed an especially money-efficient SHA-256 chip, or for that matter a pure Ⓑ-mining chip, you could perhaps remain profitable mining with it for a while, until the market caught up with you. (Does that depend on whether you use the chip yourself or sell it into the mining market where people compete with each other?)