People liked the immediacy of returns. For awhile there, ROI on mining was amazing (until the tax man showed up). For example, back in summer of 2016, I think a used R9 290 could pull in maybe $30-$50 a month depending on what you were mining and when. Used they were $200 or less (prices were inflated thanks to mining). They had about a 6 month payoff, after which point everything was pure profit . . . not counting the rising price of the tokens you mined. If you HODLed, the ROI was insane. Anyway if you took difficulty shifts and price increases off the table, you were looking at 100% profit by the end of the year, which is really, really good. That's after taking power into account. One of the problems was scaling out your investment. Big mining setups got expensive and required special power arrangements. There was basically zero risk until early 2018.
Today, ROI is much worse, but returns are more preditable. Prices and difficulty are pretty stagnant. $2/month is substantially worse, but if the up-front investment is only $210, that's %11.4 annually which beats out most stock dividends. You don't have the benefit of compounding or increased equity though, and you can't just sell the card later at the purchase price so it doesn't have the benefit of maturation like a bond. You've gotta ride it for awhile to see net profit. The real problem is that, eventually, PoW will go away on nearly every project except maybe BTC.