Once a person has made the decision that they'd like to start a company, I only see one reason to consider an MBA, and that's the networking element. OK, a second could be to have a great support infrastructure during ideation, testing, development, etc.

But, the cost/benefit just isn't there, especially not for people who already have solid professional networks -- for those, they'd be much better off diving in with a good partner.

And, if things don't work out after 1-2 years, there's always the MBA option then, and you'd have so much more knowledge about how businesses work, and what makes you excited.