That's because Twilio doesn't exist in a bubble. They're in a highly competitive sector. Their pricing has to reflect that.
They may lose money in the short-term but it allows them to become the de facto standard for telephony APIs and then they can increase their pricing or they can leverage their size to open new revenue streams.
They may lose money in the short-term but it allows them to become the de facto standard for telephony APIs and then they can increase their pricing or they can leverage their size to open new revenue streams.