Let me redirect your attention for a moment, and say that:

...I never do wrong without gaining by it...

has too many amoral implications to please me. Could he say, "I flirted with the two Misses Bertrams, and gained pleasure by it"? Or "I broke the hearts of all my sister's friends and profited with my amusement and increased cache among the London crowd"? Or "I refused my sister a settled home and found ego-stroking and diversion from her new neighbors"?