Akamai isn't giving anything away
Akamai are a Content Distribution Network. It's their job to give stuff away.
The operation of their network is funded by their clients. Their pricing structure is NDA, however I suspect you'll find it isn't too dissimilar to other CDNs where they charge their clients by data volume (i.e per GB) whilst they aim to only connect their network to the outside world via largely settlement-free peering, thereby providing them with a healthy profit margin.
you ... paying for that
Although I've outlined Akamai's position above, obviously I (or anyone else) needs visibility to their network in order to be able to download. However if those people are connected via settlement-free peering or even paid peering at a public exchange then not much is being paid for access to that data.
How little I pay is beyond the scope of this forum....
