> Without them, there's no way for people to buy into the system with real money in the first place!

Of course there is: mining. It's a very simple proceds: fiat => energy => processor => cryptocurrency.

Yet another thing that failed. Everyone was supposed to be able to mine cryptocurrency using their own computers. Instead things got so competitive that massive centralized operations using specialized hardware became the norm.

that's not true. You could be bartering. Or you could be paying for goods and services directly via crypto.

Exchanges are popular because it's easy, and also it allows you to trade _fast_. And then the exchanges figured out that they could be holding onto your cash and/or crypto, rather than, you know, actually be _just_ a location for which exchanges happen.