True if your mining XMR. But with less popular coins it's easy to earn way more then 3$ per month. Now just one ryzen 9 is earning me about 3000 ROI-COIN daily. Wich is $0.54696 every 24h at the current price of 2 Satoshi (stats from coingecko).

And prices on Roi-coin are pretty low at the moment. They were at 8 Satoshi last week. Wich is a 200% increase. So you can make about $2 a day with just one PC