My paternal grandfather won and later lost an estate - ended up in a terrace in Stoke. Dad told me that he (my father) had a float of £250 that he bet each week and he used to win between £20 and £30 profit - whilst earning £20 a week which was a well paid job as an electrical engineer in those days - as he got tips from the stables and knew who was being pulled and who was going to be pushed.
Having been out in the Shetlands for a while with little else to do but play cards he became rather adept and used to take on 'card sharks' and win in the 50's. I've seen him shuffle a pack whilst looking me in the eye and then call each card dealt, before it came from the pack.