It's worth noting that at its peak when CryptoKitties transactions hogged the Ethereum network and made it barely useable, CryptoKitties had only 14k users.
To be fair, there's a known solution to the cryptokitty scalability problem (a particular type of "plasma chain" tuned for nonfungible tokens) and this is being worked on and will likely see the light of day pretty soon. This of course does not solve the bigger problem: the small user base.
I was thinking about combining CryptoKitties and Second Life type breedable animals to make collectable ponies you could go play with and show off in virtual reality.
If I would build a system that gets DoS'd with 14k users I would get fired faster than the latest startup burns through VC money.