Yes, Danny and his paisano friends are thieves, but they never commit a crime because they find it pleasurable to be doing something wrong or out of spite for someone. They only commit crimes when they can justify them to their admittedly loose moral system. They steal the picnic foods, for example, because it was cruel of the picnickers to show off their luxury in such a way, and because they needed something to smooth the way in talking to Danny about his house that they burned down. Most of their crimes are victimless, and the rest fit into the 'rob the rich to feed the poor' mentality reminiscent of Robin Hood. The pompous restaurant owners who would have thrown food out anyway, the railroad tycoons who could afford to lose a few nails and who were destroying their precious landscape anyway, and the miser Torrelli, who had so much wine and money that whatever they took meant nothing to him anyway, are a few examples. The greatest thrill for the paisanos is when they can steal for a truly good purpose, as is the case when they raid the warehouse in order to save Teresina Cortez's children.
There is nothing that the paisanos of Monterey like more than a little wine to ease the pain of life. In Tortilla Flat, the practice is more of a science than a recreational activity. Steinbeck describes the spiritual graduation in detail near the end of chapter three, going from serious conversation at the handle of the first gallon to songs of death near the bottom of the second. Drinking was not a time killer to the paisanos, nor a means of escape from reality or anything crude like that. It was a social activity and a show of camaraderie, for every cup was distributed equally among the friends. With the wine they could talk, sing, and fight as equals and through the stories told in the haziness, they would become better friends.
Though a good number of their exploits were aimed at supporting and bettering themselves, the paisanos also endeavored to help the less fortunate whenever an opportunity arrived. In this way they were truly like the Knights of the Round Table. Though it is probably true that Pilon wanted some of the Pirate's money for himself, it is also reasonable to think that with his conscience, he would have done all that he could with the money to improve the Pirate's standard of living. In the end, they end up giving the Pirate something even more valuable—human companionship. Later, with the caporal and Teresina Cortez's children, the friends show their true selfless natures.