how he allowed his son to be raised by those who had a poor opinion of himself. Was he depressed at the time by the death of his wife, and perhaps shocked at how comparitilvely impoverished he had become after the marriage? A complete change of life after her death seems to suggets that:

A complete change of life became desirable. He quitted the militia and engaged in trade, having brothers already established in a good way in London, which afforded him a favourable opening. Chap 2

Perhaps he felt guilty about having deprived his wife of the many comforts that money brings and felt that he was making amends to his wife by letting them bring his son up in a much better manner (as far as money and privileges go).