Source of Viruses?

There seems to be no shortage of avast! updates and I occasionally look at the VPS History page. In the last week or so avast! has added literally hundreds of individual updates.
My question is where these viruses come from. Are they really someone’s effort to cause others trouble? Are some glitches?
Anyone know? Thanks

Remember this is a huge worldwide issue.

There really is that kind of numbers being generated much of it to exploit your system to use it as part of a bot net sending out spam or trying to infect others, etc. organised crime is also responsible for much of it so it isn’t just script kiddies or those writing it just for the hell of it.

David is correct. Organized crime is the largest perpetuator of malware. So much so, the US FBI has a whole division asigned to it.

Some of the updates were to correct false positive detections (not to add a lot of new ones), afik.