At launch, the supply of Koin will inflate by (at most) 15% per year (so, up to 15 million Koin will be created in the first year). The Koin that is created will be distributed to Koinos node runners (if you're interested in earning some Koin, you can learn how to run a node before the mainnet launch next year). With no fees, you need a way to incentivize node runners to join the network.
Some cryptocurrencies (like bitcoin) have a maximum supply, but all the projects I'm aware of (including bitcoin) are still creating coins until some specified future date (so they still have inflation, it's just predictable).
Koinos is being built to replace Ethereum as the world computer, so it's not concerned with being "a store of value" (like bitcoin or gold). Koinos is more concerned with creating value. Inflation will spread Koinos' market cap thinner each year, but as long as the team and community keep focus on creating value, I wouldn't worry too much about the per-Koin price.
After all, Koinos is meant to be accessible for everyone, not just line the pockets of early investors.
P.S. Does 15% inflation worry you? Can you think of a better way?