(sarcasm, btw)
Over the long term it's always been better to buy than to rent, even if the renting option is technically more efficient on the GPUs, you don't have to pay some hosting providers profit margin.
And for users that aren't running multiple agents 24/7, you should be able to fit a good user:GPU ratio.
For example (and relevant to AI) I can generate electricity on my roof at $0.20-25/kWh, batteries included. In California the electric utility can’t offer it cheaper than $0.30-0.50/kWh. Therefore at scale, electricity is actually more expensive.
There are many such examples.
Right now, there is way more scale in centralized AI than there is at the edge. But that could flip. I'd still probably put the probability that it will under 50%. But I'd also put it above zero!
What makes you so certain that economies of scale won't work the opposite way you imagine? E.g., if model improvement tapers off, but RAM costs decline (hard to believe atm, but historically likely), then eventually everyone will be able to run SOTA models on their personal hardware.
Heck, even if model sizes simply grow more slowly than RAM costs decrease, the same would happen.