What Ripple and Ethereum have in common is huge amounts of premined coins
That's why they can "compete" with Bitcoin in terms of market cap
If these coins have never entered circulation, the price would likely be times less (if not orders less). Bitcoin is also kinda premined, but 1M bitcoins of Satoshi makes only like 100/16×1=~6%. So in the very least we should subtract that value from the market cap. In this way, if 50% of Ethereum coins never entered circulation, its market cap should be halved right away. Ultimately, we should take into account only the coins that are actually traded or used in commerce. Stashed away coins swell the market cap above its real value making it mostly an irrelevant metric for crypto