CPC and Mobile devices

I start CPC campaign on Adnetwork and EXCLUDE all mobile devices, just left Desktop, Tablets. In about 1,5 hours there were about 4000 impressions and only 3 clicks. Why too low? The issue is because Bid Amount low? Or Because I excluded Mobile devices? How do traffic goes from mobile devices these days? In other hand I heard that people barely buys from mobile devices is it true?