From what I hear, commercial real estate is actually fairly easy to get into if you have the capital required--a lot for a person, but small compared to many other lines of business. One sufficiently intelligent person can certainly do it (I know one).
But I think it suffers a different kind of barrier to entry. It's an unsexy line of business, and for people who want to own property it has to compete with mindshare for the far more familiar field of residential property management. So you don't see the average Joe thinking he can buy an office building and make it profitable--what does Joe know about office buildings, compared to houses and apartments?