Just because you can go fast doesn't mean you have to. You can go the same speed for longer which to me is more fun than burning all my energy in trying to maintain 40kmh the whole way. Cycling doesn't need to be miserable. A nicer bike simply makes for better experience. Obviously the difference between a clunky wallmart mtb and a good roadie is noticable, but the difference between a good alumium or high grade steel roadie and the latest go fast carbon version isn't that large. Its the engine that counts.