At most, a warranty failure may have associated damages that could far exceed the purchase price.
(This is why FOSS licenses almost universally disclaim both warranty and liability for damages, rather than ignoring the issue. Refunding the purchase price is not the worst that can happen.)
Usually in very large software purchases, fixing problems is often much cheaper than undoing a purchase.
While technically, you may be able to legally refund a $10,000,000 software purchase in lieu of buying a plane ticket for a developer, in practice, that's not really an option anyone takes.