First... welcome. I can totally relate with your motivations. I'm a sales guy, have been for 15 years. The constant stress of meeting quotas and "what have you done for me lately" is really difficult. It does suck the life out of you. On the other hand, it provides the means to provide for your family in a way that maybe you wouldn't otherwise be able to (not everyone can be a doctor/lawyer).
I've always been a good saver, but I've also always (since I was a father anyway) had mild to more than mild anxiety about money and security. I try to tell myself that if I lost my job, I'd work hard to find a new one and would be fine. But, I do think it is the root of my want to be FI. I'd also like to find work that is more fulfilling at some point. That might be when I reach FI or am much closer to it. But, it is a nice carrot to keep me moving in a positive direction.
The stress/anxiety over money might be a part of who you are (not saying that negatively). But, I do think a quest towards FI will help relax the stress a bit and give you the opportunity to own your life, instead of it owning you.
Good luck to you and your growing family!