"Jack of all trades, master of none" is a figure of speech used in reference to a generalist: a person that is competent with many skills but is not outstanding in any particular one. (Wikipedia)
It's a very easy to become this. When I was 15 I got my first job. I worked at a grocery store. During that time I became a true master of nearly every department. I was doing the closing work, the produce department, the bakery department, checking, stocking, inventory management, unloading truck, etc. No big deal really. Anyone that works at a grocery store for a couple years gets to that point. After working there, I started working at a pharmacy for a while. Then I started working at a boat manufacturing facility before going to college. While at college I started working at a meat locker. These last two jobs I went in knowing they were temporary. I also took on a temporary position as a construction worker.Then I started working at a security development company. I had to stop because of all the insecurities I found running around that wouldn't be acknowledged. Then I went onto working as on site technical support. Part of that company got sold off and I became an employee of another company. This is another company that my personal beliefs conflicted with too much and lasted only a month. After that I took a month off and started working at Hy-Vee. This was an excellent place to work except that a previous injury took it's toll. After a back surgery and too many late nights my back couldn't take it anymore. Then I decided to focus on school. I did this until someone decided they thought I'd be the perfect administrator for them. That's when the two of us and one of his friends started Kalliki Software. At 22 years old I'm now part owner of a business that has two other employees.
The fun thing is that what I stated is only my work history. I also did a lot of open source work. I've played with the Linux kernel, Drupal development, Ubuntu packaging, server development, security development, FOSS programming in many languages, bug management, bug patching, user support, around a few thousand or so other tasks.
You'd think I'd be a pretty well rounded person. The truth is that not specializing in one thing really hurts you overall. It's great to understand a little tiny bit of everything. That's true. Understanding a little bit of everything helps you understand how things fit in together. For example, you want to know how an accountant interacts with their software so you can know what they expect when you're designing a new piece of software to replace their current system. It's also true that working in too many different areas will prevent you from ever becoming a master of one.
This is the dilemma I face as a CTO today. I've worked in so many different areas that I never let myself specialize in the one industry I really cared about. I haven't been able to master any general tasks I love doing. I've progressed in these areas but have yet to feel I've really mastered any of it. It's definitely an issue many face. As technology grows, our need to know everything and still specialize grows more. Being a database administrator means you work with databases. That should be all you ever do. In real life they're expected to also know how to make other programming tools interact with the database. They're expected to fix their neighbors computer when they break it.
As an administrator I'm expected to run servers, no the best OS to use in what situation, how to setup a mail server, how to setup virtualization, setup staging environments, built testing servers for developers, work on scripts for a few hundred tasks, make sure things never ever go down. As a FOSS advocate I'm expected to work on many different things such as what's listed above. As a CTO I'm expected to understand hiring processes, financial management, and have *hack* interpersonal skills. I'm without a doubt one of only a very large number of people fighting this.
We need to know a little about everything; we also need to make sure we pick one thing to be a true master at and a couple other things to become very proficient with. Is this going to happen? I really doubt it.
The solution: I have none.