My Vampire Girlfriend

Yes, our protagonist has already stolen tombs for more than ten years. When he was very young, his parents died, so he could only rely on begging for a living. However, he would occasionally steal from the tombs until he met his master.
As for how he learned how to steal tombs, that was another very long story. For this reason, the author kindly uses compression techniques to illustrate: First, he was caught by his master after stealing, then beat him up, saw that our main character was skillful, taught him something, and then threw him into a cemetery for an internship. For the next ten years, he spent all his time dealing with corpses, and he didn't get out of this inhuman life until his master died. As for the ten years' worth of wealth, it had all been used up by his master, including his master's gambling, whoring, and drinking.