Paul Graham, one of Silicon Valley's best-known investors and the co-founder of startup accelerator program Y Combinator, doesn't seem to be a fan of ABC's hit show "Shark Tank."

Graham believes startups should focus on building great products, not on marketing, and for that reason he thinks shows like "Shark Tank" are a distracting waste of time for entrepreneurs.

He said as much on Twitter Wednesday night, but billionaire investors Mark Cuban and Chris Sacca came back swinging.

Cuban is the owner of the Dallas Mavericks and he formerly founded a company that sold for $1 billion to Yahoo, He is also one of the "sharks" or judges on "Shark Tank" who critiques the presenting startups. 

He more or less called Graham and the startups his accelerator program has backed "entitled" and "arrogant."  

Y Combinator (YC) is designed to help startups grow rapidly by providing guidance and money to founders in exchange for equity in their companies. YC has helped now multi-billion-dollar companies like Dropbox and Airbnb get off the ground.

But the companies that go through YC--which has a very low acceptance rate are known for demanding a premium on their valuations when seeking funding from venture capitalists, hence Cuban's "entitled" jab.

But a lot of people feel accelerator programs aren't worth the equity founders give up to participate in them, which Cuban also pointed out to Graham. 

Chris Sacca is a billionaire angel investor who put early money into now-massive tech companies like Uber and Twitter. He was also a guest shark on ABC's show. He pointed out to Graham that pitching 7 million viewers every Friday night on ABC hardly seems like a waste of time for a founder.  


This story first appeared on Business Insider