Real estate is an illiquid investment that needs maintenance and taxes to be paid. A balanced investment portfolio has some liquid assets that can be quickly converted to cash to sustain the real estate when its returns are not sufficient to pay its recurring costs.

During a real estate boom, speculators can be prone to make purchases without precalculating the costs involved in the purchase and for the ongoing costs of a property. The real estate can then sometimes work against them instead of for them, realizing a loss at resale.

There is no guarantee that values will maintain themselves as society changes; megatrends can cause large scale changes. An example is the period from 1815 to 1914 in the U.K., during which real estate values did not increase although the society as a whole made massive economic progress.