Exactly as the name suggests. This person is so incredibly stupid, that he has no understanding of anything whatsoever, therefore making this person nothing else but a waste of oxygen.
Someone who is addicted to obtaining money and building wealth. A money addict and fanatic. Breadheads often work more than one full-time job, and some even participate in illicit activities to "obtain the bread".
I don't buy the schmegegge about Morty sleeping with Moira.
His version of the story was pure schmegegge.
The whole schmegegge was made up to get Liz a little bit of attention.