[diffeomorphism]

Obvious answer: because it is too expensive to offer it for "free".

Even if you had the GPUs, compute and electricity cost money:

https://medium.com/@zodhyatech/how-much-energy-does-chatgpt-...

[guidedlight]

YouTube made a loss for many years because the storage and data costs were vastly higher than their revenue, despite offering the product for free.

[edgyquant]

Those were very different market conditions though