BitCoin Supply and Alt Coin Conversion

[Triffin]

Using current values from http://coinmarketcap.com/

We have ..

41 Billion  MCAP for BitCoin  with ~16.3 million coins or ~45% of Total Crypto Market Value
51 Billion  MCAP for ALL Alt Coins or ~55% of Total Crypto Market Value ..

Since all ALT Coins are convertible to BitCoin via trading pairs on the various exchanges
The current $51 Billion ALT Coin MCAP implies that there are ~20.4 million additional BitCoins  
to satisfy conversions ..

16.3 million BitCoin
20.4 million BitCoin equivalents via ALT Coins

36.7 million BitCoins equivalent for total Crypto Market Cap ..

Since there will ( presumably ) never be more than 21 million BitCoins in existence
how does the market reconcile the above amounts/values ??  

Clearly, we can't convert the majority of ALT Coins due to BitCoin supply ..
What did I miss in Economics 101 ??

Triff ..

[Scorpion]

There are 16.3 million Bitcoins in circulation (actually a lot are held and a lot have been lost)
There are 92.2 million Ethereum in circulation (same with mined but never traded out and lost ETH)
...

Don't want to list all the millions of alt-coins with USD value. 

[Variogam]

Since there will ( presumably ) never be more than 21 million BitCoins in existence
how does the market reconcile the above amounts/values ??  

Clearly, we can't convert the majority of ALT Coins due to BitCoin supply ..
What did I miss in Economics 101 ??

Once you start selling altcoins to get Bitcoins, the exchange rate of the pair changes. Check exchanges order books, the more you sell, the lower average price you get.

[BitcoinPanther]

Since there will ( presumably ) never be more than 21 million BitCoins in existence
how does the market reconcile the above amounts/values ?? 

Clearly, we can't convert the majority of ALT Coins due to BitCoin supply ..
What did I miss in Economics 101 ??

Once you start selling altcoins to get Bitcoins, the exchange rate of the pair changes. Check exchanges order books, the more you sell, the lower average price you get.

This one explains it.  The more supply going into the exchange the more likely its price to go down.  So there is automatically a flaw on the idea of not enough bitcoin. This is a matter of supply and demand and right now you have more supply of altcoin than the demand of it so we can observe in the decrease of altcoin value and an increase of amount a single bitcoin can buy.