the idea that people will share your data benevolent right?
Not necessarily. There are a good number of providers (e.g, Pinata, Infura) of "Pinning services", which will host the data that you want to make sure it's always available. At first sight, they might seem more expensive than just using something like S3, but if you consider that there is no egress costs for files on IPFS then it might end up a lot cheaper to host content there.
If cost is a reason for concern, then the 5c/GB storage and 8c/GB egress on Pinata isn’t exactly cheaper than S3’s 2.7c/GB storage and 9c/GB egress. You can get much better mileage with something like Backblaze B2 0.6c/GB storage free egress, and couple with CloudFlare or other CDN for much lower egress (often free).