Quote from: simplyred on September 14, 2017, 09:15:53 PM

coin A
i buy a coin that has 10.000.000 marketcap and supply of 10.000.000 price is 1 dollar.

Coin B
i buy a coin that has 10.000.000 marketcap and supply of 1.000.000 price is 10 dollars

if marketcap of coin A goes to 20.000.000 and marketcap of coin B goes to 20.000.000, there is x2 gain on coin A and x2 gain on coin B.

What are you not understanding?

The marketcap is equal to the price per coin X the number of coins in existence. If there are only 10 lollipops in the world and each of them is worth $10, the total marketcap of those lollipops is $100;

As in writing this, there are 16,566,050 BTC in existence. Each BTC is worth $3248; The market cap of Bitcoin is $53,813,653,802 (16,566,050 x $3248); If the price of the bitcoin doubles right now, the total marketcap will double aswell. It's basic math.

A low supply is better because if there is more demand and less supply, there are more people buying Bitcoin and less people selling. This means that people will pay more for each coin, since its amount is limited = higher price.