Why are altcoin exchanged for btc and not for dollar?
having tons of altcoin is just like having bitcoin. If bitcoin grows, they grow. If bitcoin falls, they fall.
Isn't this pointless? Why not buying and selling alts for dollar?
I think it's all because Bitcoin is the currency of all cryptocurrency world and therefore all trades are on bitcoin
but in this way if bitcoin explodes, all will dies... there is no point on keep them... eth is also exchanged in dollar, why not the others?
Yup you are right, if the price of alts keep on bring paired with bitcoin then the movement of bitcoin will affect alts, that's why we need more usd pairing for each alts so each alts price will based on their own value, the price will also increase or decrease based on the project development. But there's also advantages of the btc pairing as you can earn more if the price of bitcoin increase while the coin hold its ground against bitcoin.