The value of real estate (barring market collapse) is fairly stable and normally goes up, not down. If I put my home on the market, my broker will suggest a price based on a LOT of comps, supply and demand, interest rates, etc. If I decide to sell my home to one of those 'we buy your home' companies, they're not going to offer WAY under market value.
Domains don't have any of that. They're not as liquid as real estate. If you do want to liquidate, you'll get pennies or dimes on the dollar unless you get really lucky. There's a giant gap between what an investor will pay vs. what an end user MIGHT pay.
Think of what goes into a real estate loan. Now imagine it's a lot riskier.