A loan, say, _is something_. You loan money to a company, they use it to build a factory, which produces, in the long run, more economic value than the cost of building it (hopefully). They pay you back, with interest. It’s a somewhat abstract something, but it is still something-by-proxy. This is generally not the case for a cryptocurrency (it might be for a lender dealing _in_ cryptocurrency, though, well, historically those usually turn out to be scams of some sort).