So why does he keep stealing more and on a larger scale, tell me please?
And if it's about Putin, personally he doesn't steal much, the reasons are described above. But he allows his inner circle to steal — if you don't feed your support group, someone else will feed them. That's how it has been and will be everywhere and at all times. Stalin, for example, often turned a blind eye to abuses in the state apparatus.
Although calling it theft is not entirely appropriate, it's more of a status rent. Moreover, for top officials, the situation is rather similar to Putin's — political ambitions are generally more important to them than material wealth. A noticeable share of purely material motivation starts somewhere on the 3rd or 4th floor of the vertical power structure.