Kurt Busch is firing back at the clothing company that sued him ... saying he lost hundreds of thousands of dollars into a brand that operated like a Ponzi scheme.
Busch is countersuing Panic Switch clothing line, saying he gave them a ton of big time exposure and money and never got it back. Kurt claims the company used his $375k investment to help pay off a $500k loan they had already taken out.
He says he introduced Panic Switch execs to other big name NASCAR drivers, who cut deals with the company but ended up backing out after PS didn't pay royalties or show proof of sales.
TMZ broke the story ... Panic switch sued Kurt last month after they say Busch's alleged violent incident with his ex-girlfriend almost destroyed the company's image.