AI infrastructure depreciates way faster than people realise, and enterprise adoption is softening

There are two things I've been looking into that don't get enough attention in the AI bull case, and I think they matter a lot for anyone holding NVIDIA, Microsoft, or anything riding on AI CapEx continuing forever. People compare AI buildout to railroads or the 90s telecom boom. I get the analogy. Those were also periods of massive overinvestment, and the narrative is that even though the bubble popped, the infrastructure ended up being useful for decades. Fibre cables from 1999 still carry traffic. Rail lines from the 1800s still move freight. The argument is basically that even if AI spend overshoots, the assets will retain value over the long run. But I started looking into how long data centre hardware actually lasts, and it doesn't match that story at all. Chips go obsolete in a couple of years. Cooling systems and networking equipment, maybe five. Even the buildings themselves can become outdated in under a decade because hardware keeps changing shape and density requirements shift. This isn't a build-it-once-and-it-pays-off-for-30-years situation. It's a treadmill. Companies will have to keep sinking hundreds of billions back in every few years just to stay where they are. The second thing I've been watching is what's happening with actual adoption on the ground. We keep hearing about exponential demand and how everyone is racing to integrate AI, but the survey data coming out lately tells a different story. Enterprise adoption rates have started dipping month over month. Around 80% of companies using AI say it hasn't moved their bottom line in any measurable way. And on the consumer side, sentiment is shifting too. Half of Americans now say they're more concerned than excited about AI, up from about a third a few years ago. If you put those two things together, the picture gets uncomfortable. On one side, you have infrastructure that needs constant replenishment and doesn't hold value the way past buildouts did. On the other, you have demand signals that are softening in exactly the places where the revenue is supposed to come from. If the corporate middle doesn't see the value yet and the general public is cooling, where does the payoff come from? I'm not saying AI is useless or that the whole thing goes to zero. But the timeline for these investments to earn a real return feels a lot tighter than the bull case assumes, and that gap between spend and payoff is where things usually break. Curious what others make of this, especially anyone with hands-on experience in data centre economics.