This may be true for games (I'm not sure), but I'm not sure it's good advice for startups in general (in case anyone was thinking that.) Throw things at the wall and see what sticks. Don't fall victim to sunk cost fallacy.
You have a point. But today's world quality and polish matters a lot. Point is before you judge make sure you provided good quality and a polished product. The idea matters a lot but if you don't present it well its good for nothing.
1. You never know if it will be a surprise hit (Crossy Road)
2. All of my game projects have made very little money, but have had unexpected side benefits that made them worthwhile.
3. It's fun. I enjoy making games more than playing them, so even if I'm wasting time, i can consider it entertainment. :)