contextual meaning of "integrate"
Solution 1:
In this case it means that individuals are adding the potential profit from renting out the new property to the change in their wealth by acquiring the property. (This is clearly speculative as the property may fail to rent, or may fail to rent for the expected value, or may be even accrue costs from rental not covered by it).
For example: if the property were to cost 200,000 (pick your favourite currency) and you expect to rent it out for 2,000 per month, then you might integrate that 2,000 per month into your overall wealth (treating the property as an asset worth 200,000) and say that you are 2,000 per month richer.