Rivian will soon reach a critical inflection point.Rivian Automotive (RIVN 0.24%) stock has performed very well thus far in 2025. Shares are up nearly 70% since the year began, with nearly all of those gains booked over the past month or two. Why is the market suddenly so bullish on Rivian stock?There are two reasons: artificial intelligence (AI) and new, cheaper models. We'll discuss both of these catalysts in a moment. But the important takeaway here is that Rivian as a business is reaching a critical inf ...