I understand your way of thinking, I actually did exactly the same. I am an automotive engineer in the netherlands but decided to make a living by making/selling donuts in uzbekistan ( of all places!)
I bought some secondhand lil orbits donut machines together with vending carts incooperating ventilation (check their website)
I cannot buy the usual "add water only instant donut mixes" here so I am now experimanting with making the mix myself.
I have varied results, the biggest problem I see is that they all taste like what we in holland call oliebollen but not like a donut like you buy from dunking donuts. This is probably because they sell raised donuts and my machines uses cake donut recipes.
if you are interested in a such a machine you can look on ebay, many second hand lil orbit units are offered there, starting from a few hundred dollars.
As you know, you only have one life so you better do something thats interesting for you and succes will come (at least I hope so!)