Naemanson, I don't know where you are from but around here there are some very talented folks that end up at open stages for one reason or another, both professional and not. An open stage is not by definition strictly amateur night. It is just open, open to all, pro or not. You can limit your open stage to nonprofessionals only, or do just about any kind of a restriction you wish with your event. Some stages have many fine and talented performers show up because they wish to advertise an up and coming concert event in the area or a new recording release. Musicians may wish to use the venue to test some new material out before a live audience, like a rehearsal. Open stages can be a venue's way of finding qualified talent to perform at their place of business, like an audition. I'm not sure if you can easily distinguish whether a particular entertainer is or isn't making their living that way by just watching them at an open stage. Assuming they are there and therefore they are amateurs for participating is a bit presumptuous. I go because there are many venues who will hire performers if they enjoy your performance at their open stage. Most stages will have a limited time that they alot you to show off your skills. It can be quite a challenge to work within those constraints. Again, there are probably as many different reasons for appearing at an open stage as there are different types of open stages to enjoy. Some will offer you a drink on the house for playing and some won't. Some places will recognize you as an entertainer and buy you a drink when you walk in the door just because they like your music. Some venues offer dinner and drinks while you perform some will only offer thanks.

I don't understand your comparison to self publishing as I am not one of those who is involved in that sort of activity. I don't think I am anyway.

A friend once told me that if they pay you $25 for playing, they treat you like you're worth $25. If they pay you $250, you get treated like $250 and if they pay you $2500 you get treated accordingly. It is sadly therefore understandable that if you get paid nothing....