Are there too many Paid-to-Click sites?

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When Adbux came out it promised about 10 ads a day and for a while did keep up. Then bux.to came out of the blue and promised something like 20 ads. Now both sites offer between 3 and 4 ads a day, often being one of the advertisers themselves. ClixMedia started and never gets more than 4 or 5 ads, DreamClix, after having about 3 or 4 daily advertisers, announes "vacations" from 28/7 to 12/8, "to improve site security". LinkGrand, cheaper for advertisers and paying only 0,003 per click, has sometimes a whole lot of 30 or more, followed by two or three days where ads are scarce. And so on, and so on... There are also a great number of "click-for-traffic" sites, that absorb plenty of ads in manual and autosurfing mode. I don't have Premium accounts, so I'm ignorant whether they are worth their money, or whether bought referrals really do pay... I'd like to know your experience with upgrading. The question is: will the great Paid-To-bubble burst? Does advertising in Internet really bring so much income that advertisers will buy always greater amounts of ad space? What do you think about? Personally, I'm optimistic, but I believe that there will be some minor earthquakes in the scene, and that some sites will have to close. Waiting for your responses :)