In Pygmalion, what does Alfred Doolittle mean by saying "he cannot afford morals" and that "middle class morality is just an excuse" for not giving him...

After
Eliza has been staying with Professor Higgins for a while, her father, Alfred Doolittle, calls
on Higgins and Pickering. Seeing how wealthy Higgins is, he believes this is an opportunity for
him to get some money from him. He offers to let Higgins keep Eliza in exchange for a
"five-pound note." This prompts Pickering to exclaim, "Have you no morals,
man?" Doolittle replies that he can't afford them. In other words, he's too poor to not try
to take advantage of a situation that presents itself to him. In his view, someone with wealth
can "afford" to have morals because he won't be...