So I work as an IT manager for a company that's about 100 people. I don't really have anyone under me anymore since we downsized. Our network is super simple. We have a VMware environment with Zero Clients for all local users and Mac laptops with View for remote users. I make decent money, but we don't really use anything besides MS Office\Internet and few other minor programs. I am bored and I would like to make a lot more money

I have a lab ready to go. I will do MCSE, then VMware, then Cisco. I have the whole thing planned out, but my confidence level is below zero. I am pretty good with what we have right now, but I feel literally scared that I won't be smart enough for more advanced stuff. My wife says that I have the aptitude for IT (network\admin) stuff and that I am being irrational about this. On the other hand I feel like when I am faced with something that goes beyond my knowledge, I fall apart. I start feeling and thinking that, "Hey this is not my thing and I'll never been as good as I need to be at this. That there are people who are super natural at this and for them all this comes easy, more or less. For the most part I know what I am doing, but I also understand that I know may be 10% of what I should know in regarding to MS, VMware, Cisco and just everything that entails being a network\system engineer. Its just something I've been doing for about 10 years, but I never got ahead. I've always been stuck at basic tech support then level 2 and then have been comfortably bored for about 4 years as the IT Manager for my firm. I spend half the day doing absolutely nothing. I know I could be learning so much, but I am stuck because I don't know if this is something i want to do for the rest of my life. I am not saying I am doing the right thing by not doing anything, but I am seriously stuck emotionally. My hear is telling my to do something else, but my brain is saying the opposite, that I should learn all this stuff and make twice what I am making right now and its just a matter of learning, practicing, etc.
Am I being irrational and because of my insecurities and lack of self confidence, I think I am going to fail before I even begin this journey or do I have valid concerns that just may be this is not what I am suppose to be doing and I will never been good at it?
PS. If there was something else I was good at, almost anything else, that allowed me to make the same money I am making now, I would do it. I don't hate IT, but my brain hurts sometimes to the point of thinking that I would rather live in a box than do this for a living for the rest of my life.
What are your thoughts?