There is a difference in how the price varies with time for coins with high inflation (like ZCASH) and low inflation (like KMD).

For coins like ZCASH, when they are launched only a handful of coins are in circulation and everyone wants to get in, leading to an artificial spike in the price post release. However, with time, large number of coins are in circulation and price goes in a downward spiral untill it is pumped by whales.

For coins like KMD with very low inflation rate (5% per year), everyone who wanted in had a chance to buy during the month long ICO. After the coin is launched the demand for the coin rises slowly and gradually as only the investors who were left out during ICO want to get in. However as time goes demand usually outgrows supply (since very little new coins are minted). and during this time price keeps steady or rise gradually untill a significant event (like acceptance by darknet markets, unexpected Polo listing etc) leads to an exponential growth in price.