Real estate isn’t that simple. Way too many layers of work and bureaucracy between wanting to build something and making it happen even when you have the cash to make it so. Many of these layers are essential, others like nimby idiots are not. We need more housing for people and it would take a huge increase in available housing to have any negligible effect on any one individuals house/property value.

As for restaurants. It’s also not that simple. Most restaurants fail in the first year or two. You have to figure out what type of food is in demand and then maybe be willing and able to shift to something else if the market gets oversaturated.