Read all your questions and to sum it up, the answer is simple: there's not one single exchange that allows USD trades into altcoins simply because cryptos can be created easily, and if that happens, imagine these exchanges being a hotbed for cash withdrawals from the devs of the coins and those supporting the coins itself almost immediately. With bitcoin being the currency these alts are pegged at, it is to ensure that the amount of money flowing out of an exchange is controlled and the exchange not operating to a loss. I mean, as an exchange operator, why would I let other people trade a relatively unknown altcoin with fiat knowing that it could just be another fraudulent way for the devs and his conspirators to make money?
Hello, sorry for the late...
I agree with your opinion, but the problem is the same with bitcoin...
you just have to exchange your altcoins in bitcoins and then in dollars ...
If you exchange an unknown altcoin in bitcoin, the person who buys your altcoin has invested dollars before to have bitcoins...
Anyway, if your altcoin is a scam, that the person loses bitcoins or dollars, finally she loses dollars...
Furthermore, an exchange plaftorm will accept an altcoin only if the project is serious.
I don't tell that the platforms should exchange your atlcoins directly herself, but if persons want to buy an altcoin, instead of buy bitcoins and deposit them before buy altcoin, they deposit directly dollars to exchange them...
With this system, each coin is independent...
Anyway, with the actual market, bitcoin will finish to be replace by another altcoin or fiat because of his saturation...his age, the transactions times, the transactions fees, ...AT a moment, he will no longer be able to follow the market and current technologies...