Chinese AI startup DeepSeek is rewriting the narrative that the AI industry needs more money and more power, by claiming to have built its base model for less than $6 million. It sparked a global sell-off that saw Nvidia shares tumble 17 percent on Monday. US President Donald Trump is calling it a "wake-up call" for the US tech industry, while OpenAI's Sam Altman says it's "invigorating to have a new competitor." But questions still remain as to how serious a threat DeepSeek will be to US companies. We take a closer look.