Earlier quoted context omitted.
I think part of the confusion is the word “currency”, which implies it’s something like USD. Ethereum’s ETH token, for example, is an asset that will appreciate if demand of the Ethereum network increases for real-world business applications (not just financial payments). That makes it much more like investing in a limited resource (ex: oil) that will go up in value. It’s still speculating, but most stock investments…
Stocks are shares in profitable companies. They have risks, sure, but they also have expected returns based on sound fundamentals and a long history of generating income.
Not always, tons of companies are losing money but the share price goes up.