Dragon's Den investors traditionally say “I'm out” when they reject an entrepreneur's pitch.
During a pitch, a Dragon may decide not to invest and announce that decision with the short phrase “I'm out”. This signals that the investor is withdrawing from consideration and will not make an offer. If every Dragon says it, the entrepreneur leaves without an investment from the panel.
The phrase is part of the show's familiar vocabulary, alongside “offer” and “equity”. It does not mean that the entrepreneur has necessarily failed in business; it only records that a particular investor, or the entire panel, has chosen not to proceed.
A televised offer is also not always the same as a completed transaction. Entrepreneurs and investors can continue negotiations after filming, and due diligence may cause an apparent deal to change. “I'm out” is therefore a decision within the pitch, not a general verdict on the company's future.