I'm willing to bet that every new investor reads about buying stocks on margin (investment loan) and thinks to themselves, "I'd be stupid not to do this!" However, we all learn (often through a painful experience) that it's a very bad thing for an individual to mess around with.
The problem is unequal risk and reward. Let's say you have $10,000 to invest and you can borrow another $10,000 at 6.5%.
Scenario 1 - You invest your $10,000 cash and borrow nothing
If your investment goes up 8%, you make $800 and end up with $10,800
If your investment stays flat, you make $0 and end up with $10,000
If your investment goes down 8%, you lose $800 and end up with $9,200
Scenario 2 - You invest $20,000 (50% cash, 50% borrowed)
If your investment goes up 8%, you make $1,600, pay $650 interest and end up with $10,950
If your investment stays flat, you make $0, pay $650 interest and end up with $9,350
If your investment goes down 8%, you lose $1,600, pay $650 interest and end up with $7,750
Even worse, after experiencing Scenario 2, you'd realize margin is a bad idea and now you have to grow your $7,750 without leverage by 30% just to get back to even after an 8% decline. Also, if your loan is through a broker, as your investment goes down you may be subject to a "margin call" forcing you to sell low.
I'm not experienced in real estate investment, but I'd say the biggest reason that a leveraged real estate investment is much less risky is that the value of the property and (even more importantly) the rent you can demand are much, much less volatile, so if you can conservatively say that your expected rent will cover your fixed expenses and interest, you can be relatively sure that you're not going to lose your shirt.