Same boat as a couple others. I have a 9-5 @ a very large company, where I'm fairly high up. Thing is, unlike most corporate jobs, I actually really dig it.
Love my boss & small team, the work I'm doing is both continually interesting & challenging, the pay & benefits are fantastic (like stupid to walk away from right now), and the accompanying lifestyle is pretty plum (20-40% from home, never work past 6pm, rarely travel anymore). Plus my work is fairly complex and analytical, so I don't have to micro-manage or babysit teenager-like idiots (i.e. I get to cherry pick smart people to work with & for me).
That said, I know that as I continue to move up the ranks, it won't always be as low-key and flexible. So that's my motivation for dabbling in IM -- pay down debts, have some supplemental income, and build passive income-generating assets.
The downside is that my day job setup is so sweet right now that I find myself only doing IM activities that I find interesting & engaging. Which means I'm building much slower over the last year than I originally planned due to lacking a real sense of urgency and find myself focusing more on short-term campaigns rather than building long-term scalable infrastructure. Something of a Catch-22.
But hey, all of that just sounds like lazy self-justification. I won't lie, I definitely envy the guys here netting $100k+/month and know that while I might be in a very comfortable situation right now, I will probably never scale to that level doing what I'm doing without out putting in 10+ yrs of time and being very, very lucky.