Those wealthy enough to be in real estate in my country have in many cases made more money sitting on their arses for a couple of years than I expect to make in my whole lifetime. You can literally sit on a piece of unwanted real estate if you have sufficient capital and wait to see if it accrues added "value". Sure you may have to pay some legal fees occasionally but all you really need do is be wealthy in the first place. You're buying a scarce resource that, provided you can take a long view and aren't forced to sell at a particular time, will almost certainly not decrease in value.
Now, domaining is the same. But here the scarcity is dubious as the registries can alter that whenever they want to print some more money for themselves. Buy-in is a lot less costly but predicting the upside appears to be concomitantly more difficult.
Most people domaining don't have sufficient capital to do it right or are to late to the market. But I don't see how this changes the underlying similarity. The same is true in real estate.
Buying real estate and buying domains takes effort.
If you think it's easy give it a try and see how easy it is.
It's not. Most of the people buying domains that they think might sell won't sell them ever for any price.