A lot of trojans are like off-the-shelf kits that anyone can grab. The technical skills amount to convincing someone to run an executable (email, malicious USB keys, poorly managed advertising networks, etc) and then clicking a few buttons in a GUI to connect to them and do what you will.

For the slightly more technical, you've got frameworks like metasploit which can perform network attacks, but even that is getting much more like a kit these days. Port scan for services, fingerprint them, check database for known vulnerabilities, automatically attempt to exploit known vulnerabilities, deploy payload (the trojan).

A typical drug dealer would make more money working at McDonald's, so why don't they? People are weird.

Once you've been convicted of something, or even arrested really, you have few legal options to support yourself.

> A typical drug dealer would make more money working at McDonald's, so why don't they?

I think a substantial share of those drug dealers who aren't working formal-economy jobs as well are also drug addicts that would not be able to keep such jobs particularly well even if they weren't drug dealers, and/or convicts that wouldn't be likely to be offered such jobs if they chose to pursue them.