Because, they want to save what money they have. However, it is up to you as a producer to find a business model that works if you want to seriously make income. Sometimes contrary to what a lot of people believe the best way is not always signing with some major record label because even they have stipulations as to how a producer gets paid. You have to think who are the artist that you are workig with. Example (up andcoming rapper meets you) They figure oh wow he can help me out and I can get his name out there with a track. Now the same artist meets Just Blaze and really wants to work with him. Now because that artist understands there level of notariety is far different than just blaze they say, "If Only I had the money to pay him". Now that being said how do you get yourself out there to get that notariety, you network with people and promote yourself as a business (Production company, or whatever you do) instead of just thinking-->I want to sell beats, Think---> I'm promoting a business in which I sell beats. The question from here is how do I find customers, network, go where artists go, Seminars, Concerts, (Even if you aren't going after artists that are preforming, other artist's will be there.) Think of these things as business trips.
Next The Online market, You promote but do not do it in a way where you are obnoxiously Saying "Yo I HAVE BEATS FOR SALE FOR THE LOW". Ofcourse I'm not saying you do that i'm just giving an example. start convos with artists on the net and get to know them, you want to know them anyway afterall there could be a great connection with there music in yours. than direct them to your site, or wherever and if they feel the work and see that you are running a business, they will be more likely to buy from you.