If he's making money consistently, then he isn't lucky

Arbitrage is very different from buying into a currency as if it were a stock though.

That's what I always tell people. A bitcoin or etherium or dogecoin or whatever they have is essentially valueless because it can't be exchanged easily for goods and services. 100% of it's value is derived from how much real, useable money you can exchange it for and nothing else.

Huh? Who invests in a currency thinking it'll go up in value? Most have inflation on purpose, your money is literally eaten away by "investing in" currency.

The goal of an investment is to make money. Nobody owns a dollar hoping it'll appreciate in value.

At best you might buy dollars as a hedge if you live in a country where the currency is inflating rapidly and you want to be safe from it. But nobody is buying into dollars as if they were stocks the way people do with crypto, which is what the husband in the OP probably did with ETH.

Currency isn't supposed to be an investment. If it is, then it's failed its job as a currency. There are cryptocurrencies that do a much better job at being a currency than eth or btc, which are TERRIBLE currencies, but great for gambling

So you're investing in loans. Not the US Dollar. That's an entirely different thing.

a lot of it.