Back in the early 80s, I had a very brief career working for a small family of mutual funds. It led nowhere career-wise, but I got licensed as a securities dealer and learned a lot that helped later on. After that, I got an MBA and learned even more.
While working at Megacorp, I continued to read about investing and retirement planning, but probably not as much as I should have. Talked with coworkers occasionally, usually just about the investment options in the 401K and AA strategy. Went to a few retirement/investment seminars at Megacorp, which were pretty useless. No family that I could talk to about such things. DW and I just kept maxing out our 401Ks, plowing money into equity funds, and we both stayed our whole career at employers with DB pensions, which seems to have worked out quite well.
I discovered FIRECalc and this forum in 2012 about a year before I retired. I had already sort-of determined (via my own Excel model) that our numbers were good-to-go (or very close) and was looking for validation anywhere I could find it. At the same time, I was working with our Fidelity Private Client Group rep who had me feeding numbers into the RIP tool with favorable results, but I wanted other validation.
After reading on the ER forum for a while, I realized how little I knew about the finer points of transitioning from the accumulation phase into retirement. So I've stuck around a while, learned a ton, and avoided lots of mistakes. Great resource and one of the most civil discussion forums I've ever encountered.