Cerebras Systems went public on Wednesday and the stock popped 68 percent on day one, valuing the AI chipmaker at roughly $95 billion. If you're wondering whether this is sustainable or just another AI hype cycle ready to implode, you're asking the right question.The company priced its IPO at $185 per share. It opened for trading at $350 and briefly touched $386 before settling back. Retail investors piled in. Institutional money piled in. Everyone wants a piece of the AI infrastructure story, and Cerebras has positioned itself as the challenger to Nvidia's GPU dominance.Here's what Cerebras actually does: they build massive AI training chips that are supposedly 100 times faster than traditional GPUs. They've got partnerships with OpenAI and Amazon Web Services. Nvidia itself invested in the company a few months ago, which tells you the incumbents are paying attention.The bull case is straightforward. AI is eating the world, and whoever builds the picks and shovels wins. Cerebras is making big, expensive chips that hyperscalers need to train frontier models. If demand stays strong, the valuation could pencil out.The bear case is equally straightforward. A $95 billion market cap on day one is pricing in a lot of growth that hasn't happened yet. Nvidia already dominates this market with scale, software ecosystem, and customer lock-in. Cerebras is fighting uphill against an entrenched competitor with 10x the resources. And we've seen this movie before: hot IPO, massive day-one pop, reality sets in six months later when growth doesn't materialize.The underwriters, Morgan Stanley, Citigroup, Barclays, and UBS, have a greenshoe option to buy an additional 4.2 million shares at the IPO price. At the opening price of $350, that's roughly $700 million in profit for the banks. They don't leave money on the table, and this will materially lift their quarterly earnings. The banks made out like bandits.For retail investors looking at this, here's the reality: if you didn't get IPO allocation, you're buying at $350 or wherever it's trading now, not $185. You're paying the premium that early investors and insiders already captured. That doesn't mean it can't go higher, Nvidia went up 10x after people said it was overvalued, but you're starting from a much tougher entry point.Is this the AI bubble? Probably parts of it are. Is Cerebras the real deal? Maybe. They've got real technology, real customers, and real revenue. But a $95 billion valuation on day one leaves very little room for error. If execution stumbles, if Nvidia crushes them on the next product cycle, if AI spending slows, this stock could give back half its value in a quarter.The smart play here isn't to chase the momentum on day two. It's to watch how the next few earnings reports go, see if revenue growth justifies the valuation, and wait for a pullback. If Cerebras is the real deal, there will be plenty of time to get in at a reasonable price. If it's hype, you'll be glad you waited.Day-one IPO pops are fun to watch. They're terrible entry points for most investors. Let the dust settle.