Depending on how you do it. I'm currently in the first year of a rather well-ranked MBA program.

Classes are Tuesday and Thursday nights from 6pm to 10pm. The rest of my time is spent working on starting my company. And this degree is going to cost me $40k total, all of which is tax-deductible, of course.

I'd say its a pretty good deal.

Not all MBA's are two-year programs. Here in Europe most MBA programs are just one year long, which makes much more sense.

I'm currently getting my MBA at a really good one-year program, and I'm using it as a testbed and launchpad for my new company. If in the course of a year, with all of the connections and opportunities at the University, I can't get enough traction I'll cut my losses and get a regular (but non-consulting and non-finance) job.

So it's not necessarily one or the other. Doing both is pretty tough, but certainly not impossible.

I have done both.

Doing an MBA is so different than starting a business.

With an MBA, there is no risk, its a fun, intellectual 2 year experience. Even better if you have a business education background, chill out, enjoy the networking.

Starting a company on the other hand is a grind, ups and down everyday.

My MBA gave me the business confidence that I knew pretty much everything that is teachable in business. However, be aware, only 20% or so of business is teachable, much is not yet understood, or dangerously subjective to be applicable to a particular situation.

Funnily enough investment is one of the things they teach you about when doing an MBA, so when you finish it you can work out if it was worth it :)