Actually I agree with much of what you have written; although JA seemed tio find him perfectly acceptable. I think it goes back to the definition of a gentleman in the Regency era. The most important criteria seems to be that a gentleman does not work. Lawyers, for example, could not charge a fee but could take renumeration as a "gift" without losing thier gentleman status if theyn had it. Ditto for physicians. If Bingley's income is from investments and he does not actively involve himself in the running of the bisiness (if that is the source of the income) then he could be labelled a gentleman. Darcy is a gentleman despite being actively involved in the running/management of his estate because that is one of the few work-related activities a gentleman could pursue. That obviously springs from land as the generator of wealth until the Industrial Revolution.
