I don't think Pelosi is a Marxist. She simply plays on TV, as there are enough clueless voters (of all demographic groups) in her district to fall for it and reliably re-elect her.
Pelosi uses and abuses her position to enrich herself and her husband. Everything else is an act to enable her to continue that.
Harry Reid does the same thing. Frankly, there are few politicians on either side of the aisle that run for office for altruistic reasons.
It's a human trait. It only becomes a character flaw when the level of avarice rises to the level of Pelosi and Reid.