Pip’s life in London makes things difficult for Herbert because they live and spend a lot of time together and Pip has unlimited funds but Herbert does not.
Herbert Pocket comes from a wealthy family, but he is not wealthy. At the moment, most of the wealth seems to be ties up with Miss Havisham. Herbert is trying to make a living on his own, mostly by looking about him. Yet Pip’s spending habits seem to influence him, and as Pip runs up debt so does he.
In my confidence in my own resources, I would willingly have taken Herbert's expenses on myself; but
Herbert was proud, and I could make no such proposal to him. So, he got into difficulties in every direction, and continued to look about him. (ch 34)
Herbert does not seem to have any prospects, although he apparently tries to find some. Since he doesn’t really have connections, his looking about him to gain experience does not do much. So he has no job, and runs up debt. He gets so depressed that at one point he considers going to America to make his fortune. There don’t seem to be many opportunities for him there.
Herbert’s situation is a good example of how being a gentleman is not a ticket to the easy life. As a gentleman, Herbert is not really supposed to work. He can’t just go get a job. He has no profession and no prospect for one. In fact, he might never have gotten off the ground if Pip had not bought him a place in the company in Cairo. Of course, he would not knowingly take anything from Pip, so Pip never told him where it came from. Yet he found a way to look out for his friend.