There are a lot more people than you think that simply don't invest their money, instead they keep it in savings accounts. My aunt is one of those people. She got a large inheritance and basically kept it in a savings account for 20 years. My mom got the same inheritance and bought investment properties with it and now its worth 10x. I think it comes down to the fact that a lot of people are risk averse or feel that investments are too complicated for them.
10x? I'm not familiar with real estate. How does one earn 10x in that time frame. Even with a price to rent ratio of 1 to 15 and assuming housing prices double over that period, you still aren't at 10x, and that doesn't include maintenance, taxes, closing fees, etc.
Leverage. Let's say the inheritance was 50k. You make that a 10% down payment on a 500k house. Assume rent covers your interest on the loan, taxes, etc. 10 years later the house appreciates 100% to 1M. You sell the house.
Even if you're risk averse, a limited time, guaranteed rate investment available in most banks will give you more than the checking account rate. (as long as you're happy to lock the money for 6+ months)