...because becoming a gentleman of leisure *was* considered a grand ambition in that time and place - there was a stigma attached to being a tradesman, as the Bingley sisters and even Darcy make clear in the Netherfield chapters. A particular individual might feel differently, of course... I do think that "buying an estate" implied that a man was planning on giving up whatever trade or profession he had been carrying on before, but Julie could answer this better than I can.