https://ipfs.io/images/ipfs-applications-diagram.png for some examples of applications using IPFS. Visit https://ipfs.io/ for more info.
I've personally used it for storing large binaries outside of git. My build process requires using some binaries and fetching them by hash is much better than fetching them from some url.
This is a good indicator of a technology's novelty, but it has zero correlation with the product/market fit.
Internet = Once curiosity, small, for geeks
Internet = Success
Filecoin = Is curiosity, small, for geeks
It is untrue that automatically follows Filecoin = SuccessIPFS doesn't really have a killer app people actually care about as long as we're not actually interplanetary - the internet connection from any point to another on the planet is generally good enough.
Here is a subforum dedicated to discussing use cases of IPFS. https://discuss.ipfs.io/c/ecosystem/applications-of-ipfs/16
It could turn out to be a flop, but the only people that would lose would be accredited investors who, according to regulations, should know better. I would say Filecoin has at least as good of a chance of succeeding as any ordinary VC investment.