They're the same thing. Swapping, exchanging, trading assets, they're all synonyms. What you're referring to is how regular one trades, which in the case with retail trading is probably everyday?
Exactly. When we come to the exchange just to buy some asset and keep it in our wallet until a certain time, then I agree in this regard, DEX is quite suitable for this. If we are talking about high-frequency trading as a full-fledged activity, then CEX is much better and more convenient for this activity. As we know, the most popular type of trading is day trading, so for the majority, the rejection of centralized services.
Well, sure, truly decentralized exchange doesn't come with all the commercialized shitcoins a centralized exchange provides, but I don't believe that someone who wants to buy bitcoin cares much about that.
The use of exchanges is not limited to bitcoin alone. Especially during periods of high volatility, when many tokens generally outperform bitcoin in terms of profitability. That is why they like to speculate with such tokens, they can give a lot of profit in a short period of time.