Pip and Herbert joined a London Social club for young gentleman known as the Finches of the Grove.
As Pip became accustomed to his expectations, he tried to follow the lead of the other gentleman in his tutoring circle. Startop suggested that they join a club, and they did. Pip never realized that purpose of the Finches.
[The] object of [the Finches] I have never divined, if it were not that the members should dine expensively once a fortnight, to quarrel among themselves as much as possible after dinner, and to cause six waiters to get drunk on the stairs. (ch 34)
Pip notes that the members behave foolishly and spend their money foolishly. From the influence of the Finches, Pip learns a lot of bad habits. He begins amassing debt by buying things without paying for them. He has no idea how much money he has access to or how to get it. He simply bumbles around making bad decisions.