I find that you can make the most money in the things that are not obvious. My experiences:
In college in the mid eighties working for near
minimum wage I read a mother earth news article from 1976 on how to run a sprout business. There were many doubters (100%) but I started my sprout business. Within 2 years I was clearing 7K/Yr for 15 hours a week, this was in 1986.
Moving forward to 2000 in a different location with 3 kids, a mortgage, 40 acres and a ton of credit card debt, I thought about the "Buy a jeep for 75.00" ads I remember from popular mechanics. While I knew that was not true I did think that the surplus property must go somewhere. With a 750.00 loan I bought some stuff that turned out to be worth 10,000 to some military nuts.
When that started to take too much time, in 2002 I bought 10 cars (one at a time) at the state auction and turned those into 5K.
Now I am debt free and a little bit less motivated or just slowing down, but every now and again I think of an idea. My smoker uses a
proprietary electric starter which is outrageously overpriced. Within 90 minutes on the web I located a comparable starter. So maybe I'll start a eBay business selling these.
My point is money can be made in the least obvious ways. Also do not believe your buddies, usually they are negative. And remember packaged money programs pay far less than your own ideas.
I hope this helps someone out there.
Oh I'll add this one reason I don't do more nowadays is I have a certain skill set which is in demand in the middle east (Kuwait, Iraq and Afghanistan) and for the times that I do this I am compensated well. So if you have a good skill your greatest wealth builder is your job. But for extra cash think a little outside of the box, be willing to take a few risks.