To make some sort of (of course flawed) comparison: You want a nice house. You can drive around the neighborhood, look at what houses exist and inspect the ho

To make some sort of (of course flawed) comparison: You want a nice house. You can drive around the neighborhood, look at what houses exist and inspect the house you are interested in from roof to cellar bevor making an offer. You adjust your price for the parts you think need renovating, market conditions etc. Banks will gladly finance the deal, you don't need to have very much money of your own. Or you buy an empty plot, buy a lot of materials, hire people to turn the materials into a house of your specifications. In many established neighborhoods it's very hard to even get an empty plot. Maybe you don't find the materials or people in the quantity or quality you want. Maybe your plans are not that good. Maybe the weather is bad and you take much longer than you planned, and you can't stop at half a house when you run out of money. If everything goes well you can get a better house for less money, but you have to be able to afford the risk.